Method for managing D2D terminal group in wireless communication system and apparatus for same

ABSTRACT

The present invention discloses a method for managing a device to device (D2D) terminal group in a wireless communication system and an apparatus for the same. In detail, a method for managing a device to device (D2D) terminal group in a wireless communication system may include the steps of: receiving, by a first terminal which belongs to the D2D terminal group, a discovery signal from a second terminal which belongs to the D2D terminal group on a physical sidelink discovery channel (PSDCH); calculating, by the first terminal, a position of the second terminal by using the discovery signal; and displaying, by the first terminal, the position of the second terminal based on the position of the first terminal.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the National Stage filing under 35 U.S.C. 371 of International Application No. PCT/KR2015/003675, filed on Apr. 13, 2015, which claims the benefit of U.S. Provisional Application No. 61/978,976, filed on Apr. 13, 2014 and 61/978,977, filed on Apr. 13, 2014 the contents of which are all hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a wireless communication system, and more particularly, to a method for managing a device to device (D2D) terminal group in a wireless communication system and an apparatus for the same, which support (D2D) communication.

BACKGROUND ART

A mobile communication system has been developed to provide a voice service while guaranteeing activity of a user. However, the mobile communication system extends an area up to a data service as well as a voice and at present, a short phenomenon of a resource is caused due to an explosive increase of traffic and uses require a higher-speed service, and as a result, a more developed mobile communication system is required.

Requirements of a next-generation mobile communication system largely need to support accommodation of explosive data traffic, an epochal increase of transmission rate per user, accommodation of the significantly increased number of connection devices, very low end-to-end latency, and high energy efficiency. To this end, various technologies have been researched, which include dual connectivity, massive multiple input multiple output (MIMO), in-band full duplex, non-orthogonal multiple access (NOMA), super wideband supporting, device networking, and the like.

DISCLOSURE Technical Problem

An object of the present invention proposes a method for managing a D2D terminal group for managing a position of a group member terminal based on a specific D2D terminal in a D2D group constituted by a plurality of D2D terminals.

Another object of the present invention proposes a method for managing a D2D terminal group for maintaining a connection between a terminal which deviates from coverage and a group member terminal when a D2D group member terminal deviates from predetermined coverage.

Yet another object of the present invention proposes a method for managing a D2D terminal group, for a terminal which suffers from an emergency situation to manage an adjacent terminal as a D2D terminal group when the emergency situation occurs.

Technical objects of the present invention are not limited to the above-described object and other technical objects that have not been described above will become evident to those skilled in the art from the following description.

Technical Solution

In one aspect of the present invention, a method for managing a device to device (D2D) terminal group in a wireless communication system may include the steps of: receiving, by a first terminal which belongs to the D2D terminal group, a discovery signal from a second terminal which belongs to the D2D terminal group on a physical sidelink discovery channel (PSDCH); calculating, by the first terminal, a position of the second terminal by using the discovery signal; and displaying, by the first terminal, the position of the second terminal based on the position of the first terminal.

In another aspect of the present invention, a first terminal for managing a device to device (D2D) terminal group in a wireless communication system supporting device to device (D2D) communication may include: a display unit for displaying information; a radio frequency (RF) unit for transmitting/receiving a wireless signal; and a processor, wherein the processor may be configured to receive a discovery signal from a second terminal which belongs to the D2D terminal group on a physical sidelink discovery channel (PSDCH), calculate the position of the second terminal by using the discovery signal, and display a position of the second terminal based on the position of the first terminal.

Preferably, the method may further include transmitting, by the first terminal, a warning message to the second terminal on a physical sidelink shared channel (PSSCH) when the second terminal is spaced apart from the first terminal by a predetermined distance.

Preferably, when a third terminal which belongs to the D2D terminal group deviates from D2D coverage of the D2D terminal group, an anchor terminal for relaying data between the third terminal and a terminal which belongs to the D2D terminal group among the terminals which belong to the D2D terminal group may be configured.

Preferably, the third terminal and the anchor terminal may be connected through a cellular link and the anchor terminal and the terminal which belongs to the D2D terminal group may be connected through a D2D link.

Preferably, the anchor terminal may be selected as a terminal having reference signal received power (RSRP), a signal to noise ratio (SNR), or a signal to interference plus noise ratio (SINR) for the D2D link between the terminals which belong to the D2D terminal group, which is the highest.

Preferably, the anchor terminal may be selected as a terminal that transits a D2D synchronization signal.

Preferably, the anchor terminal may be selected as a terminal that transmits a physical sidelink broadcast channel (PSBCH).

In another aspect of the present invention, a method for managing a device to device (D2D) terminal group in a wireless communication system supporting device to device (D2D) communication may include the steps of: receiving, by a first terminal, a discovery signal from an adjacent terminal on a physical sidelink discovery channel (PSDCH); and transmitting, by the first terminal, to a server D2D terminal group information on the adjacent terminal transmitting the discovery signal when the first terminal detects event occurrence, wherein the D2D terminal group may be constituted by one or more terminals that receive the discovery signal of the first terminal, and the D2D group information may include a D2D identifier (ID).

In another aspect of the present invention, a first terminal for managing a device to device (D2D) terminal group in a wireless communication system supporting device to device (D2D) communication may include: a radio frequency (RF) unit for transmitting/receiving a wireless signal; and a processor, wherein the processor may be configured to receive a discovery signal from an adjacent terminal on a physical sidelink discovery channel (PSDCH) and transmit D2D terminal group information for the adjacent terminal that transmits the discovery signal to a server when detecting event occurrence, the D2D terminal group may be constituted by one or more terminals that receive the discovery signal of the first terminal, and the D2D group information may include a D2D identifier (ID).

Preferably, the event occurrence may include executing an emergency reporting function of the first terminal or sensing occurrence of an emergency situation through a sensor mounted on the first terminal.

Preferably, the method may further include transmitting, by the first terminal, an emergency signal to a second terminal which belongs to the D2D terminal group, wherein the emergency signal may include an indication notifying that the corresponding signal is the emergency signal.

Preferably, the emergency signal may be transmitted through a system information block, a master information block, or an emergency resource area pre-allocated through a radio resource control (RRC) signal.

Preferably, the D2D group information may further include an emergency situation type, an emergency situation occurrence time, an emergency situation occurrence position, or emergency situation strength information.

Advantageous Effects

According to embodiments of the present invention, a position of a D2D group member terminal can be continuously managed based on a D2D signal.

Besides, according to the embodiment of the present invention, even when the D2D group member terminal deviates from predetermined coverage, a connection between the terminal which deviates from the coverage and the group member terminal can be maintained.

Further, according to the embodiment, it is possible to effectively cope with an emergency situation by managing a terminal that transmits an adjacent D2D signal as a D2D group when the emergency situation occurs.

The technical effects of the present invention are not limited to the above-described effects and other technical effects that have not been described above will be evidently understood by those skilled in the art from the following description.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to help understanding of the present invention, the accompanying drawings which are included as a part of the Detailed Description provide embodiments of the present invention and describe the technical features of the present invention together with the Detailed Description.

FIG. 1 illustrates an M2M system according to an ETSI technical standard to which the present invention can be applied.

FIG. 2 illustrates one example of a network structure of an evolved universal terrestrial radio access network (E-UTRAN) to which the present invention can be applied.

FIG. 3 illustrates a radio interface protocol structure between a terminal and the E-UTRAN in a wireless communication system to which the present invention can be applied.

FIG. 4 illustrates a structure of a radio frame in the wireless communication system to which the present invention can be applied.

FIG. 5 is a diagram illustrating a resource grid for one downlink slot in the wireless communication system to which the present invention can be applied.

FIG. 6 illustrates a structure of a downlink subframe in the wireless communication system to which the present invention can be applied.

FIG. 7 illustrates a structure of an uplink subframe in the wireless communication system to which the present invention can be applied.

FIG. 8 is a flowchart illustrating a process of establishing RRC connection in the wireless communication system to which the present invention can be applied.

FIG. 9 is a flowchart illustrating a process of reconfiguring RRC connection in the wireless communication system to which the present invention can be applied.

FIG. 10 is a diagram illustrating an uplink resource allocating process of a terminal in the wireless communication system to which the present invention can be applied.

FIG. 11 is a diagram for conceptually describing D2D communication in the wireless communication system to which the present invention can be applied.

FIG. 12 illustrates one example of various scenarios of D2D communication to which a method proposed by the present specification can be applied.

FIG. 13 is a diagram for describing a distributed discovery resource allocating method in the wireless communication system to which the present invention can be applied.

FIG. 14 is a diagram schematically illustrating a discovery process of a terminal using the distributed discovery resource allocating method in the wireless communication system to which the present invention can be applied.

FIG. 15 is a diagram for describing a method for transmitting/receiving signaling for D2D direct communication in the wireless communication system to which the present invention can be applied.

FIG. 16 is a diagram for describing a method for transmitting downlink control information for D2D direct communication in the wireless communication system to which the present invention can be applied.

FIG. 17 is a diagram illustrating a scenario of measuring a position of UE using a D2D signal/channel according to an embodiment of the present invention.

FIG. 18 is a diagram for describing a spread delay between UEs according to an embodiment of the present invention.

FIGS. 19 and 20 are diagrams for describing a method of measuring a distance between operating UE and target UE by using a D2D signal/channel according to an embodiment of the present invention.

FIGS. 21 to 24 are diagrams for describing a method of measuring a position of the target UE by using the D2D signal/channel according to an embodiment of the present invention.

FIGS. 25 and 26 are diagrams for describing a method of measuring the position of the target UE or the distance from the target UE by using the D2D signal/channel according to an embodiment of the present invention.

FIG. 27 illustrates a user interface for implementing a D2D terminal group managing method according to an embodiment of the present invention.

FIGS. 28 to 34 are diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

FIG. 35 is a diagram illustrating a user interface at the time of implementing a D2D ID collecting method according to an embodiment of the present invention.

FIGS. 36 and 37 are diagrams illustrating a D2D ID collecting method according to an embodiment of the present invention.

FIG. 38 is a block diagram of a wireless communication apparatus according to an embodiment of the present invention.

FIG. 39 is a block diagram of another terminal according to an embodiment of the present invention.

BEST MODE

Some embodiments of the present invention are described in detail with reference to the accompanying drawings. A detailed description to be disclosed along with the accompanying drawings are intended to describe some embodiments of the present invention and are not intended to describe a sole embodiment of the present invention. The following detailed description includes more details in order to provide full understanding of the present invention. However, those skilled in the art will understand that the present invention may be implemented without such more details.

In some cases, in order to avoid that the concept of the present invention becomes vague, known structures and devices are omitted or may be shown in a block diagram form based on the core functions of each structure and device.

In this specification, a base station has the meaning of a terminal node of a network over which the base station directly communicates with a device. In this document, a specific operation that is described to be performed by a base station may be performed by an upper node of the base station according to circumstances. That is, it is evident that in a network including a plurality of network nodes including a base station, various operations performed for communication with a device may be performed by the base station or other network nodes other than the base station. The base station (BS) may be substituted with another term, such as a fixed station, a Node B, an eNB (evolved-NodeB), a Base Transceiver System (BTS), or an access point (AP). Furthermore, the device may be fixed or may have mobility and may be substituted with another term, such as User Equipment (UE), a Mobile Station (MS), a User Terminal (UT), a Mobile Subscriber Station (MSS), a Subscriber Station (SS), an Advanced Mobile Station (AMS), a Wireless Terminal (WT), a Machine-Type Communication (MTC) device, a Machine-to-Machine (M2M) device, or a Device-to-Device (D2D) device.

Hereinafter, downlink (DL) means communication from an eNB to UE, and uplink (UL) means communication from UE to an eNB. In DL, a transmitter may be part of an eNB, and a receiver may be part of UE. In UL, a transmitter may be part of UE, and a receiver may be part of an eNB.

Specific terms used in the following description have been provided to help understanding of the present invention, and the use of such specific terms may be changed in various forms without departing from the technical spirit of the present invention.

The following technologies may be used in a variety of wireless communication systems, such as Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Time Division Multiple Access (TDMA), Orthogonal Frequency Division Multiple Access (OFDMA), Single Carrier Frequency Division Multiple Access (SC-FDMA), and Non-Orthogonal Multiple Access (NOMA). CDMA may be implemented using a radio technology, such as Universal Terrestrial Radio Access (UTRA) or CDMA2000. TDMA may be implemented using a radio technology, such as Global System for Mobile communications (GSM)/General Packet Radio Service (GPRS)/Enhanced Data rates for GSM Evolution (EDGE). OFDMA may be implemented using a radio technology, such as Institute of Electrical and Electronics Engineers (IEEE) 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, or Evolved UTRA (E-UTRA). UTRA is part of a Universal Mobile Telecommunications System (UMTS). 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE) is part of an Evolved UMTS (E-UMTS) using evolved UMTS Terrestrial Radio Access (E-UTRA), and it adopts OFDMA in downlink and adopts SC-FDMA in uplink. LTE-Advanced (LTE-A) is the evolution of 3GPP LTE.

Embodiments of the present invention may be supported by the standard documents disclosed in at least one of ETSI (European Telecommunications Standards Institute), IEEE 802, 3GPP, and 3GPP2, that is, radio access systems. That is, steps or portions that belong to the embodiments of the present invention and that are not described in order to clearly expose the technical spirit of the present invention may be supported by the documents. Furthermore, all terms disclosed in this document may be described by the standard documents.

A concept and a technology in which an object is connected to a network or information is shared by configuring a communication network among objects by using a communication device attached to the object may be called machined to machine communication.

The ETSI calls the machine to machine communication as Machine-to-Machine (M2M) and the M2M is defined as communication among two or more objects in which human direct intervention is not particularly required.

In the specification, an M2M server calls a server for M2M communication and calls a fixed station or a mobile station. The M2M server may exchange data and control information by communicating with M2M devices and/or other M2M server. Further, in the present invention, an M2M gateway calls a device that serves as a connection point which enters another network from one network when a network connected with the M2M device and a network connected with the M2M server are different from each other.

In addition, in the specification, a term “entity” may be used to call hardware such as the M2M device, the M2M gateway, and the M2M server or used to call software components of an M2M application layer and an M2M (common) service layer described below.

FIG. 1 illustrates an M2M system according to an ETSI technical standard to which the present invention can be applied.

An M2M system according to an ETSI TS M2M technical standard defines a common M2M service framework for various M2M applications. The M2M applications may call software components that implement M2M service solutions such as e-Health, City Automation, Connected Consumer, and Automotive. In the M2M system, functions commonly required for implementing the various M2M applications may be provided and the commonly required functions may be called an M2M service or an M2M common service. When the M2M common service is used, the M2M application may be easily implemented without reconfiguring a basic service framework for each M2M application.

The M2M service is provided in the form of a service capability (SC) and the M2M application may access the SC through an open interface and use the M2M service provided by the SC. The SC may be a set of functions of the M2M service, which may be used when the M2M application is provided on the service framework. A service capability (SC) entity and a service capability (SC) layer may be collectively called the SC.

The SC may be expressed as xSC. Herein, x may be expressed as one of N, G, and D and represents at which network (and/or server), gateway, or device the SC is present. For example, the NSC represents the SC which is present on the network and/or server and the GSC represents the SC which is present on the gateway.

The M2M application may be present on the network, the gateway, or the device.

The M2M application which is present on the network or present in direct connection with the server is called an M2M network application and may be briefly represented by a network application (NA). For example, the NA is software implemented in direct connection to the server and may serve to communicate with and manage the M2M gateway or the M2M device.

The M2M application which is present on the device is called an M2M device application and may be briefly expressed by a device application (DA). For example, the DA is software driven in the M2M device and may transfer sensor information, and the like to the NA.

The M2M application which is present on the gateway is called an M2M gateway application and may be briefly expressed by a gateway application (GA). For example, the GA may serve to manage an M2M gateway and provide the service capability (SC) to the DA. An application entity (AE) and an application layer may be collectively called the M2M application.

Referring to FIG. 1, a high level architecture for the M2M may be divided into a network domain and a device and gateway domain.

The network domain may be constituted by an access network, a core network, an M2M service capability (SC), an M2M application, network management functions, and an M2M management function.

The access network is an entity that enables the M2M device and the gateway domain to communicate with the core network. Examples of the access network include xDSL (Digital Subscriber Line), HFC (Hybrid Fiber Coax), a satellite, GERAN, UTRAN, eUTRAN, Wireless LAN, WiMAX, and the like.

The core network is an entity that provides functions including Internet protocol (IP) connection, service and network control, interconnection, roaming, and the like. The core network includes a 3rd Generation Partnership Project (3GPP) core network, an ETSI Telecommunications and Internet converged Services and Protocols for Advanced Networking (TISPAN) core network, a 3GPP2 core network, and the like.

Therefore, in an example of FIG. 1, the core network and the access network provides connections among the respective entities rather than performing an M2M function. M2M communication may be performed among the M2M SCs in the network domain and the device and gateway domain through the core network and the access network and the M2M application of each domain may transmit and receive a signal or information through the M2M SC of each domain.

The M2M SC may provide an M2M common service function (CSF) which may be shared in multiple M2M network applications and exposes the M2M service through the open interface to allow the M2M applications to use the M2M service. An M2M SC entity may be appreciated as one instance of a common service function (CSF) and provides a subset of the common service functions (CSFs) which may be used and shred by the M2M applications. An M2M service capability layer (SCL) may represent a layer including the M2M SC entity.

The M2M application is an entity that may operate service logic and use the M2M SC through the open interface. The M2M application layer may represent a layer including the application and related operational logic.

The network management functions are constituted by functions required for managing the core network and the access network. The functions include provisioning, supervision, fault management, and the like.

The M2M management function is constituted by a function required for managing the M2M SC in the network domain. A specific M2M SC is used to manage the M2M device and the gateway. A set of the M2M management function includes a function for an M2M service bootstrap. The function is called an M2M service bootstrap function (MSBF) and is implemented in an appropriate server. A role of the MSBF enables a bootstrap of permanent M2M service layer security credential in the M2M SC in the M2M device (alternatively, the M2M gateway) and the network domain. Permanent security credential bootstrapped by using the MSBF (e.g., an M2M root key) is stored at a safe position called an M2M authentication server (MAS). The server may be an AAA server. The MSBF may be included in the MAS and further, may communicate with the MAS through an appropriate interface (e.g., a diameter when the MAS is AAA). The corresponding permanent security credential established in a D/G M2M node during the bootstrapping is stored in a secured environment domain of the D/G M2M node.

The device and gateway domain is constituted by the M2M device, an M2M area network, and the M2M gateway.

The M2M device is an entity that operates the M2M device application through the M2M SC. The M2M device may include the M2M application and/or the M2M SC.

The M2M device may be connected with the network domain through the access network (that is, communicate with the M2M server of the network domain). The M2M device performs procedures including registration, authentication, authorization, management, and provisioning with the network domain. The M2M device may provide the service in connection with other devices (e.g., a legacy device, and the like) hidden from the network domain.

The M2M device may be connected with the network domain through the M2M gateway (that is, communicate with the M2M server of the network domain). When the M2M device is connected with the network domain through the M2M gateway, the M2M gateway operates like a proxy. One example of a proxy procedure of the M2M gateway corresponds to the authentication, the authorization, the management, and the provisioning. The M2M device is connected with the M2M gateway by using the M2M area network.

The M2M device may be connected to the network domain through multiple M2M gateways.

The M2M area network provides connectivity between the M2M device and the M2M gateway. In this case, the network between the M2M gateway and the M2M server and the network between the M2M device and the M2M gateway may be different from each other. For example, the M2M area network may be implemented by using a personal area network (PAN) technology such as IEEE802.15.1, Zigbee, Bluetooth, IETF ROLL, or ISA100.11a and a local network technology such as power line communication (PLC), M-BUS, wireless M-BUS, KNX, or the like.

The M2M gateway is an entity that manages the M2M application through the M2M SC and provides the service to the M2M application. The M2M gateway may include the M2M application and/or the M2M SC. The M2M gateway may represent an entity having a gateway function among the M2M devices.

The M2M gateway may serve as the proxy between the M2M device and the network domain and provide the service in connection with other devices (e.g., the legacy device, and the like) hidden from the network domain. For example, the M2M gateway may operate an application that collects and handles various information (e.g., information from a sensor and a contextual parameter).

An M2M system architecture illustrated in FIG. 1 is just an example and a name of each entity may vary. For example, in a system (called an oneM2M system) according to a oneM2M technical standard, the M2M SC may be called an M2M common service entity (CSE) and a service capability layer (SCL) may be called a common service layer (CSL). Further, the M2M application may be called the application entity (AE) and the M2M application layer may be briefly called the application layer. Similarly, the name of each domain may also vary. For example, in the oneM2M system, the network domain may be called an infrastructure domain and the device and gateway domain may be called a field domain.

As illustrated in FIG. 1, the M2M system may be appreciated as a layer structure including the M2M application layer and the M2M SC layer for the M2M communication.

Meanwhile, even in the 3GPP, a standardization work is progressed by using a name called machine type communications with respect to M2M communication. In the 3GPP, the MTC is defined in the form of data communication which one or more objects are concerned with, in which human intervention is not particularly required.

In the specification, the MTC may be appreciated as the same meaning as the M2M communication, Internet of things (IoT), and device-to-device (D2D).

Hereinafter, in order to clearly describe the present invention, 3GPP LTE/LTE-A is primarily described, but a technical feature of the present invention is not limited thereto.

General System to which Present Invention can be Applied

FIG. 2 illustrates an example of the network structure of E-UTRAN (evolved universal terrestrial radio access network) to which the present invention may be applied.

An E-UTRAN system is an advanced version of the existing UTRAN system, and may be a 3GPP LTE/LTE-A system, for example. E-UTRAN consists of eNBs that provide a control plane protocol and a user plane protocol to UEs, and the eNBs are connected via the X2 interface. The X2 user plane interface X2-U is defined between the eNBs. The X2-U interface provides non-guaranteed delivery of user plane PDUs (packet data units). The X2 control plane interface X2-CP is defined between two neighbor eNBs. The X2-CP performs the following functions: context transfer between eNBs, control of user plane tunnels between a source eNB and a target eNB, transfer of handover-related messages, uplink load management and the like. An eNB is connected to user equipment UE through a radio interface and is connected to an Evolved Packet Core (EPC) through the S1 interface. The S1 user plane interface (S1-U) is defined between the eNB and the serving gateway (S-GW). The SI control plane interface (S1-MME) is defined between the eNB and the MME (Mobility Management Entity). The S1 interface performs the following functions: EPS (Enhanced Packet System) Bearer Service Management function, NAS (Non-Access Stratum) Signaling Transport function, Network Sharing Function, MME Load balancing Function and the like. The S1 interface supports many-to-many relations between eNBs and MMEs/S-GWs.

FIG. 3 illustrates the configurations of a control plane and a user plane of a radio interface protocol between the E-UTRAN and a UE in the wireless communication system to which the present invention can be applied.

FIG. 3(a) shows the respective layers of the radio protocol control plane, and FIG. 3(b) shows the respective layers of the radio protocol user plane.

Referring to the FIG. 3, the protocol layers of a radio interface protocol between the E-UTRAN and a UE can be divided into an L1 layer (first layer), an L2 layer (second layer), and an L3 layer (third layer) based on the lower three layers of the Open System Interconnection (OSI) reference model widely known in communication systems. The radio interface protocol is divided horizontally into a physical layer, a data link layer, and a network layer, and vertically into a user plane for data transmission and a control plane for signaling.

The control plane is a passage through which control messages that a UE and a network use in order to manage calls are transmitted. The user plane is a passage through which data (e.g., voice data or Internet packet data) generated at an application layer is transmitted. The following is a detailed description of the layers of the control and user planes in a radio interface protocol.

The control plane is a passage through which control messages that a UE and a network use in order to manage calls are transmitted. The user plane is a passage through which data (e.g., voice data or Internet packet data) generated at an application layer is transmitted. The following is a detailed description of the layers of the control and user planes in a radio interface protocol.

The MAC layer of the second layer provides a service to a Radio Link Control (RLC) layer, located above the MAC layer, through a logical channel. The MAC layer plays a role in mapping various logical channels to various transport channels. And, the MAC layer also plays a role as logical channel multiplexing in mapping several logical channels to one transport channel.

The RLC layer of the second layer supports reliable data transmission. The RLC layer performs segmentation and concatenation on data received from an upper layer to play a role in adjusting a size of the data to be suitable for a lower layer to transfer the data to a radio section. And, the RLC layer provides three kinds of RLC modes including a transparent mode (TM), an unacknowledged mode (UM) and an acknowledged mode (AM) to secure various kinds of QoS demanded by each radio bearer (RB). In particular, the AM RLC performs a retransmission function through automatic repeat and request (ARQ) for the reliable data transfer. The functions of the RLC layer may also be implemented through internal functional blocks of the MAC layer. In this case, the RLC layer need not be present.

A packet data convergence protocol (PDCP) layer of the second layer performs a header compression function for reducing a size of an IP packet header containing relatively large and unnecessary control information to efficiently transmit such an IP packet as IPv4 and IPv6 in a radio section having a small bandwidth. This enables a header part of data to carry mandatory information only to play a role in increasing transmission efficiency of the radio section. Moreover, in the LTE/LTE-A system, the PDCP layer performs a security function as well. This consists of ciphering for preventing data interception conducted by a third party and integrity protection for preventing data manipulation conducted by a third party.

A Radio Resource Control (RRC) layer located at the bottom of the third layer is defined only in the control plane and is responsible for control of logical, transport, and physical channels in association with configuration, re-configuration, and release of Radio Bearers (RBs). The RB is a logical path that the second layer provides for data communication between the UE and the E-UTRAN. To accomplish this, the RRC layer of the UE and the RRC layer of the network exchange RRC messages. To Configure of Radio Bearers means that the radio protocol layer and the characteristic of channels are defined for certain service and that each of specific parameters and operating method are configured for certain service. The radio bearer can be divided signaling radio bearer (SRB) and data radio bearer (DRB). The SRB is used as a path for transmission RRC messages in the control plane, and the DRB is used as a path for transmission user data in the user plane.

A Non-Access Stratum (NAS) layer located above the RRC layer performs functions such as session management and mobility management.

One cell of the eNB is set to use a bandwidth such as 1.25, 2.5, 5, 10 or 20 MHz to provide a downlink or uplink transmission service to UEs. Here, different cells may be set to use different bandwidths.

Downlink transport channels for transmission of data from the network to the UE include a Broadcast Channel (BCH) for transmission of system information, a Paging Channel (PCH) for transmission of paging messages, and a downlink Shared Channel (DL-SCH) for transmission of user traffic or control messages. User traffic or control messages of a downlink multicast or broadcast service may be transmitted through DL-SCH and may also be transmitted through a downlink multicast channel (MCH). Uplink transport channels for transmission of data from the UE to the network include a Random Access Channel (RACH) for transmission of initial control messages and an uplink SCH (UL-SCH) for transmission of user traffic or control messages.

Logical channels, which are located above the transport channels and are mapped to the transport channels, include a Broadcast Control Channel (BCCH), a Paging Control Channel (PCCH), a Common Control Channel (CCCH), a dedicated control channel (DCCH), a Multicast Control Channel (MCCH), a dedicated traffic channel (DTCH), and a Multicast Traffic Channel (MTCH).

FIG. 4 illustrates the structure of a radio frame in a wireless communication system to which an embodiment of the present invention can be applied.

3GPP LTE/LTE-A support a radio frame structure type 1 which may be applicable to Frequency Division Duplex (FDD) and a radio frame structure which may be applicable to Time Division Duplex (TDD).

FIG. 4(a) illustrates the radio frame structure type 1. A radio frame consists of 10 subframes. One subframe consists of 2 slots in a time domain. The time taken to send one subframe is called a Transmission Time Interval (TTI). For example, one subframe may have a length of 1 ms, and one slot may have a length of 0.5 ms.

One slot includes a plurality of Orthogonal Frequency Division Multiplexing (OFDM) symbols in the time domain and includes a plurality of Resource Blocks (RBs) in a frequency domain. In 3GPP LTE, OFDM symbols are used to represent one symbol period because OFDMA is used in downlink. An OFDM symbol may be called one SC-FDMA symbol or symbol period. An RB is a resource allocation unit and includes a plurality of contiguous sub carriers in one slot.

FIG. 4(b) illustrates the frame structure type 2. The radio frame structure type 2 consists of 2 half frames. Each of the half frames consists of 5 subframes, a Downlink Pilot Time Slot (DwPTS), a Guard Period (GP), and an Uplink Pilot Time Slot (UpPTS). One subframe consists of 2 slots. The DwPTS is used for initial cell search, synchronization, or channel estimation in UE. The UpPTS is used for channel estimation in an eNB and to perform uplink transmission synchronization with UE. The guard period is an interval in which interference generated in uplink due to the multi-path delay of a downlink signal between uplink and downlink is removed.

The structure of a radio frame is only one example. The number of subcarriers included in a radio frame or the number of slots included in a subframe and the number of OFDM symbols included in a slot may be changed in various ways.

FIG. 5 is a diagram illustrating a resource grid for one downlink slot in a wireless communication system to which an embodiment of the present invention can be applied.

Referring to FIG. 5, one downlink slot includes a plurality of OFDM symbols in a time domain. It is described herein that one downlink slot includes 7 OFDMA symbols and one resource block includes 12 subcarriers for exemplary purposes only, and the present invention is not limited thereto.

Each element on the resource grid is referred to as a resource element, and one resource block (RB) includes 12×7 resource elements. The number of RBs NDL included in a downlink slot depends on a downlink transmission bandwidth.

The structure of an uplink slot may be the same as that of a downlink slot.

FIG. 6 illustrates the structure of a downlink subframe in a wireless communication system to which an embodiment of the present invention can be applied.

Referring to FIG. 6, a maximum of three OFDM symbols located in a front portion of a first slot of a subframe correspond to a control region in which control channels are allocated, and the remaining OFDM symbols correspond to a data region in which a physical downlink shared channel (PDSCH) is allocated. Downlink control channels used in 3GPP LTE include, for example, a physical control format indicator channel (PCFICH), a physical downlink control channel (PDCCH), and a physical hybrid-ARQ indicator channel (PHICH).

A PCFICH is transmitted in the first OFDM symbol of a subframe and carries information about the number of OFDM symbols (i.e., the size of a control region) which is used to transmit control channels within the subframe. A PHICH is a response channel for uplink and carries an acknowledgement (ACK)/not-acknowledgement (NACK) signal for a Hybrid Automatic Repeat Request (HARD). Control information transmitted in a PDCCH is called Downlink Control Information (DCI). DCI includes uplink resource allocation information, downlink resource allocation information, or an uplink transmission (Tx) power control command for a specific UE group.

A PDCCH may carry information about the resource allocation and transport format of a downlink shared channel (DL-SCH) (this is also called an “downlink grant”), resource allocation information about an uplink shared channel (UL-SCH) (this is also called a “uplink grant”), paging information on a PCH, system information on a DL-SCH, the resource allocation of a high layer control message, such as a random access response transmitted on a PDSCH, a set of transmission power control commands for individual UE within specific UE group, and the activation of a Voice over Internet Protocol (VoIP), etc. A plurality of PDCCHs may be transmitted within the control region, and UE may monitor a plurality of PDCCHs. A PDCCH is transmitted on a single Control Channel Element (CCE) or an aggregation of some contiguous CCEs. A CCE is a logical allocation unit that is used to provide a PDCCH with a coding rate according to the state of a radio channel. A CCE corresponds to a plurality of resource element groups. The format of a PDCCH and the number of available bits of a PDCCH are determined by an association relationship between the number of CCEs and a coding rate provided by CCEs.

An eNB determines the format of a PDCCH based on DCI to be transmitted to UE and attaches a Cyclic Redundancy Check (CRC) to control information. A unique identifier (a Radio Network Temporary Identifier (RNTI)) is masked to the CRC depending on the owner or use of a PDCCH. If the PDCCH is a PDCCH for specific UE, an identifier unique to the UE, for example, a Cell-RNTI (C-RNTI) may be masked to the CRC. If the PDCCH is a PDCCH for a paging message, a paging indication identifier, for example, a Paging-RNTI (P-RNTI) may be masked to the CRC. If the PDCCH is a PDCCH for system information, more specifically, a System Information Block (SIB), a system information identifier, for example, a System Information-RNTI (SI-RNTI) may be masked to the CRC. A Random Access-RNTI (RA-RNTI) may be masked to the CRC in order to indicate a random access response which is a response to the transmission of a random access preamble by UE.

FIG. 7 illustrates the structure of an uplink subframe in a wireless communication system to which an embodiment of the present invention can be applied.

Referring to FIG. 7, the uplink subframe may be divided into a control region and a data region in a frequency domain. A physical uplink control channel (PUCCH) carrying uplink control information is allocated to the control region. A physical uplink shared channel (PUSCH) carrying user data is allocated to the data region.

A Resource Block (RB) pair is allocated to a PUCCH for one UE within a subframe. RBs belonging to an RB pair occupy different subcarriers in each of 2 slots. This is called that an RB pair allocated to a PUCCH is frequency-hopped in a slot boundary.

RRC Connection Procedure

In order to manage the mobility of the terminal in the NAS layer positioned on the control planes of the terminal and the MME, an EPS mobility management (EMM) registered state and an EMM deregistered state may be defined. The EMM registered state and the EMM deregistered state may be applied to the terminal and the MME. Like a case of turning on the power of the terminal for the first time, an initial terminal is in the EMM deregistered state and the terminal performs a process of registering the terminal in the corresponding network through an initial attach procedure in order to access the network. When the attach procedure is successfully performed, the terminal and the MME is transitioned to the EMM registered state.

Further, in order to manage signaling connection between the terminal and the network, an EPS connection management (ECM) connected state (ECM-CONNECTED) and an ECM idle (ECM-IDLE) state may be defined. The ECM connected state and the ECM idle state may also be applied to the terminal and the MME. ECM connection is constituted by RRC connection configured between the terminal and the base station and S1 signaling connection configured between the base station and the MME. An RRC state represents whether the RRC layer of the terminal and the RRC layer of the base station are logically connected to each other. That is, when the RRC layer of the terminal and the RRC layer of the base station are connected to each other, the terminal is in the RRC connected state (RRC_CONNECTED). When the RRC layer of the terminal and the RRC layer of the base station are not connected to each other, the terminal is in the RRC idle state (RRC_IDLE).

The network may determine the presence of the terminal which is in the ECM connected state by the unit of the cell and effectively control the terminal. On the contrary, the network may not determine the presence of the terminal which is in the ECM idle state and the core network (CN) manages the terminal by the unit of a tracking area which is a larger region unit than the cell. When the terminal is in the ECM idle state, the terminal performs discontinuous reception (DRX) configured by the NAS by using a uniquely allocated ID in the tracking area. That is, monitors a paging signal at a specific paging opportunity for each terminal-specific paging DRX cycle to receive a broadcast of system information and paging information. Further, when the terminal is in the ECM idle state, the network does not have context information of the terminal. Therefore, the terminal in the ECM idle state may perform a terminal based mobility associated procedure such as cell selection or cell reselection without receiving a command of the network. When a position of the terminal in the ECM idle state is different from a position known by the network, the terminal may notify the position of the corresponding terminal to the network through a tracking area update (TAU) procedure. On the contrary, when the terminal is in the ECM connected state, the mobility of the terminal is managed by the command of the network. In the ECM connected state, the network knows the cell to which the terminal belongs. Accordingly, the network may transmit and/or receive data to or from the terminal, control the mobility such as handover of the terminal and perform cell measurement for a neighboring cell.

As described above, the terminal needs to be transitioned to the ECM connected state in order to receive a general mobile communication service such as voice or data. Like the case of turning on the power of the terminal for the first time, the initial terminal is in the ECM idle state similarly to the EMM state and when the terminal successfully registers in the corresponding network through the initial attach procedure, the terminal and the MME are transitioned to the ECM connected state. Further, when the terminal is registered in the network, but traffic is deactivated and a radio resource is not thus allocated, the terminal is in the ECM idle state and when new uplink or downlink traffic occurs in the corresponding terminal, the terminal and the MME are transitioned to the ECM connected state through a service request procedure.

FIG. 8 is a flowchart illustrating a process of establishing RRC connection in the wireless communication system to which the present invention can be applied.

The terminal transmits an RRC connection request message for requesting the RRC connection to the base station (S510). The base station transmits an RRC connection setup message as a response to the RRC connection request (S802). The terminal enters an RRC connection mode after receiving the RRC connection setup message.

The terminal transmits an RRC connection setup complete message used for verify successful completion of establishing the RRC connection (S803).

FIG. 9 is a flowchart illustrating a process of reconfiguring RRC connection in the wireless communication system to which the present invention can be applied.

RRC connection reconfiguration is used to modify the RRC connection. The RRC connection reconfiguration is used to RB establish/modify/release, handover execution, and measurement setup/modification/release.

The base station transmits the RRC connection configuration message for modifying the RRC connection (S901). The terminal transmits to the base station an RRC connection reconfiguration complete message used for verify successful completion of the RRC connection reconfiguration as a response to the RRC connection reconfiguration (S902).

Uplink Resource Allocation Procedure

In a 3GPP LTE/LTE-A system, a scheduling based data transmitting/receiving method of the base station is used in order to maximize utilization of the resource. This means that when there is data which the terminal will transmit, uplink resource allocation is preferentially requested to the base station and the data may be transmitted by using only an allocated uplink resource.

FIG. 10 is a diagram illustrating an uplink resource allocating process of a terminal in the wireless communication system to which the present invention can be applied.

In order to efficiently use an uplink radio resource, the base station needs to know transmit what kind of data and how much data is to be transmitted to the uplink. Therefore, the terminal may transfer information on uplink data which the terminal autonomously intends to transmit and the base station may allocate the uplink resource to the corresponding terminal based thereon. In this case, the information on the uplink data which the terminal transfers to the base station as an amount of the uplink data stored in a buffer of the terminal is called a buffer status report (BSR). When the resource on the PUSCH is allocated at a current TTI and a reporting event is triggered, the terminal transmits the BSR by using an MAC control element.

FIG. 10(a) illustrates in which the terminal allocates the uplink resource for the actual data when the uplink radio resource for the buffer status report is not allocated to the terminal. That is, since a terminal that is transitioned from a DRX mode to an active mode has no previously allocated data resource, the terminal needs to request a resource for uplink data with SR transmission through the PUCCH as a start and in this case, an uplink resource allocation procedure of 5 steps is used.

Referring to FIG. 10(a), as a case in which a PUSCH resource for transmitting the BSR is not allocated, the terminal first transmits a scheduling request (SR) to the base station in order to be allocated with the PUSCH resource (S1001).

The scheduling request is used for the terminal to request the PUSCH resource in order to be allocated with the PUSCH resource for uplink transmission when the radio resource is not scheduled on the PUSCH at the current TTI while reporting event occurs. That is, when a regular BSR is triggered, but the terminal has no uplink radio resource for transmitting the BSR to the base station, the terminal transmits the SR on the PUCCH. The terminal transmits the SR on the PUCCH or starts a random access procedure according to whether the PUCCH resource for the SR is configured. In detail, the PUCCCH resource in which the SR may be transmitted may be determined by a combination of a PRB in which the SR is transmitted, a cyclic shift (CS) applied to a basic sequence (e.g., a ZC sequence) for frequency domain spread of the SR, and an orthogonal code (OC) for time domain spread of the SR. Further, the PUCCH resource may include SR transmission periodicity and SR subframe offset information. The PUCCH resource in which the SR may be transmitted may be terminal-specifically configured by a high layer (e.g., the RRC layer).

When the terminal receives from the base station a UL grant for the PUSCH resource for transmitting the BSR (S1002), the terminal transmits the BSR triggered through the PUSCH resource allocated by the UL grant (S1003).

The base station verifies the amount of data which the terminal will actually transmit to the uplink through the BSR and transmits the UL grant for the PUSCH resource for actual data transmission to the terminal (S1004). The terminal that receives the UL grant for the actual data transmission transmits actual uplink data to the base station through the allocated PUSCH resource (S1005).

FIG. 10(b) illustrates a process in which the terminal allocates the uplink resource for actual data when the uplink radio resource for the BSR is allocated to the terminal.

Referring to FIG. 10(b), as a case in which the PUSCH resource for transmitting the BSR has already been allocated, the terminal transmits the BSR through the allocated PUSCH resource and transmits the scheduling request to the base station simultaneously therewith (S1006). Subsequently, the base station verifies the amount of data which the terminal will actually transmit to the uplink through the BSR and transmits the UL grant for the PUSCH resource for the actual data transmission to the terminal (S1007). The terminal that receives the UL grant for the actual data transmission transmits the actual uplink data to the base station through the allocated PUSCH resource (S1008).

Device-to-Device (D2D) Communication

A Device-to-Device (D2D) communication technology means a scheme in which terminals which are geographically proximate to each other directly communicate with each other without using an infrastructure such as the base station. As the D2D communication technology, technologies primarily using an unlicensed frequency band have been developed, such as Wi-Fi Direct and Bluetooth. However, development and standardization of the D2D communication technology using a licensed frequency band are in progress for the purpose of improving frequency use efficiency of a cellular system.

In general, the D2D communication as a term which denotes communication between things or the M2M communication is limitedly used, but the D2D communication in the present invention may include all of communication among various types of devices having a communication function, such as a smart phone or a personal computer in addition to a simple device having the communication function.

FIG. 11 is a diagram for conceptually describing D2D communication in the wireless communication system to which the present invention can be applied.

FIG. 11(a) illustrates a base station based communication scheme in the related art and terminal 1 (UE 1) may transmit data to the base station on the uplink and the base station may transmit data to terminal 2 (UE 2) on the downlink. The communication scheme may be referred to as an indirect communication scheme through the base station. In the indirect communication scheme, a Un link (as a link between the base stations or a link between the base station and a repeater, may be referred to as a backhaul link) which is a link defined in a wireless communication system in the related art and/or a Un link (as a link between the base station and the terminal or a link between the repeater and the terminal, may be referred to as an access link) may be associated.

FIG. 11(b) as one example of the D2D communication illustrates a UE-to-UE communication scheme and UE-to-UE data exchange may be performed without using the base station. The communication scheme may be referred to as a direct communication scheme between the devices. The D2D direct communication scheme has advantages including a decrease in latency, use of less radio resources, and the like as compared with the indirect communication scheme through the base station.

FIG. 12 illustrates one example of various scenarios of D2D communication to which a method proposed by the present specification can be applied.

A scenario of the D2D communication may be largely divided into (1) an Out-of-coverage network, (2) a partial-coverage network, and (3) an in-coverage network according to whether UE 1 and UE 2 are positioned in coverage/out of coverage.

The case of the in-coverage network may be divided into an in-coverage-single-cell and an in-coverage-multi-cell according to the number of cells corresponding to the coverage of the base station.

FIG. 12(a) illustrates one example of an Out-of-coverage network scenario of the D2D communication.

An out-of-coverage network scenario represents D2D communication between D2D terminals without control of the base station.

In FIG. 12(a), it may be illustrated that only UE 1 and UE 2 are present and UE 1 and UE 2 perform direct communication.

FIG. 12(b) illustrates one example of a partial-coverage network scenario of the D2D communication.

The partial-coverage network scenario represents performing the D2D communication between the D2D terminal positioned in the network coverage and the D2D terminal positioned out of the network coverage.

In FIG. 12(b), it may be illustrated that UE 1 positioned in the network coverage and UE 2 positioned out of the network coverage communicate with each other.

FIG. 12(c) illustrates one example of an in-coverage-single-cell scenario and FIG. 12(d) illustrates one example of an in-coverage-multi-cell scenario.

The in-coverage network scenario represents that the D2D terminals perform the D2D communication through the control of the base station in the network coverage.

In FIG. 12(c), UE 1 and UE 2 are positioned within the same network coverage (alternatively, cell) and perform the D2D communication under the control of the base station.

In FIG. 12(d), UE 1 and UE 2 are positioned in the network coverage, but positioned in different network coverage. In addition, UE 1 and UE 2 perform the D2D communication under the control of the base station managing each network coverage.

Hereinafter, the D2D communication will be described in more detail.

The D2D communication may operate in the scenario illustrated in FIG. 3, but in general, the D2D communication may operate in the coverage and out of the coverage. A link used for the D2D communication (UE-to-UE direct communication) may be referred to as D2D link, direct link, or sidelink, but hereinafter, the link used for the D2D communication will be collectively called and described as the sidelink for easy description.

Sidelink transmission may operate in an uplink spectrum in the case of FDD and operate in an uplink (alternatively, downlink) subframe in the case of TDD. Time division multiplexing (TDM) may be used for multiplexing the sidelink transmission and uplink transmission.

The sidelink transmission and the uplink transmissions do not simultaneously occur. The sidelink subframe partially or totally overlapped with the uplink subframe or UpPTS used for the uplink transmission, the sidelink transmission does not occur. Further, sidelink transmission and reception do not also simultaneously occur.

In the case of a structure of a physical resource used for the sidelink transmission, a structure of an uplink physical resource may be similarly used. However, a last symbol of the sidelink subframe is constituted by a guard period not to be used for the sidelink transmission.

The sidelink subframe may be configured by an extended CP or a normal CP.

The D2D communication may be largely divided into discovery, direct communication, and synchronization.

1) Discovery

The D2D discovery may be applied in the network coverage (including Inter-cell and Intra-cell). In inter-cell discovery, both synchronous and asynchronous cell deployments may be considered. The D2D discovery may be used for various commercial purposes including advertisement, coupon issue, friend finding, and the like for a terminal within a proximate area.

When UE 1 plays a role of transmitting a discovery message, UE 1 transmits the discovery message and UE 2 receives the discovery message. Transmission and reception roles of UE 1 and UE 2 may be exchanged with each other. The discovery message transmitted from UE 1 may be received by one or more UE(s) such as UE 2.

The discovery message may include a single MAC PDU and herein, the single MAC PDU may include a UE identifier (ID) and an application ID.

As a channel for transmitting the discovery message, a physical sidelink discovery channel (PDSCH) may be defined. As a structure of the PDSCH, a PUSCH structure may be reused.

As a resource allocation method for the D2D discovery, two types (Type 1 and Type 2) may be used.

In the case of Type 1, the base station may allocate a resource for transmitting the discovery message by a non-UE specific scheme.

In detail, a radio resource pool for discovery transmission and reception constituted by a plurality of subframe sets and a plurality of resource block sets is allocated within a specific period (hereinafter, referred to as ‘discovery period’) and discovery transmission UE arbitrarily selects a specific resource in the radio resource pool and thereafter, transmits the discovery message.

The periodic discovery resource pool may be allocated for transmitting a discovery signal by a semi-static scheme. Configuration information of the discovery resource pool for the discovery transmission includes the discovery period, subframe set and resource block set information which may be used for transmitting the discovery signal within the discovery period, and the like. The configuration information of the discovery resource pool may be transmitted to the UE by high layer signaling. In the case of in-coverage UE, the discovery resource pool for the discovery transmission may be configured by the base station and notified to the UE by using RRC signaling (e.g., a system information block (SIB)).

The discovery resource pool allocated for the discovery within one discovery period as a time-frequency resource block having the same size may be multiplexed by TDM and/or FDM and the time-frequency resource block having the same size may be referred to as ‘discovery resource’. The discovery resource may be divided by the unit of one subframe and include two physical resource blocks (PRBs) per slot in each subframe. One discovery resource may be used for transmitting a discovery MAC PDU by one UE.

Further, the UE may repeatedly transmit the discovery signal within the discovery period for transmitting one transport block. The MAC PDU transmitted by one UE may be repeatedly (e.g., repeatedly four times) contiguously or non-contiguously within the discovery period (that is, the radio resource pool). The number of transmission times of the discovery signal for one transport block may be transmitted to the UE by the high layer signaling.

The UE may arbitrarily select a first discovery resource in a discovery resource set which may be used for repeated transmission of the MAC PDU and other discovery resources may be determined in association with the first discovery resource. For example, a predetermined pattern may be previously set and the next discovery resource may be determined according to the previously set pattern according to a position of the discovery resource which the UE first selects. Or, the UE may arbitrarily select each discovery resource in the discovery resource set which may be used for the repeated transmission of the MAC PDU.

In Type 2, the resource for transmitting the discover message is UE-specifically allocated. Type 2 is subdivided into Type 2A (Type-2A) and Type 2B (Type-2B). Type 2A is a scheme in which the base station allocates the resource every transmission instance of the discovery message within the discovery period and Type 2B is a scheme in which the base station allocates the resource by a semi-persistent scheme.

In the case of Type 2B, RRC_CONNECTED UE requests allocation of the resource for transmitting the D2D discovery message to the base station through the RRC signaling. In addition, the base station may allocate the resource through the RRC signaling. When the UE is transitioned to the RRC_IDLE state or when the base station withdraws the resource allocation through the RRC signaling, the UE release a transmission resource which is allocated most recently. As described above, in the case of Type 2B, the radio resource may be allocated by the RRC signaling and activation/deactivation of the radio resource allocated by the PDCCH may be determined.

The radio resource pool for receiving the discovery message may be configured by the base station and notified to the UE by using the RRC signaling (e.g., the system information block (SIB)).

The UE that receives the discovery message monitors both the discovery resource pools of Type 1 and Type 2 in order to receive the discovery message.

2) Direct Communication

An application area of the D2D direct communication includes even a network coverage edge-of-coverage area as well as network in-coverage and out-of-coverage areas. The D2D direct communication may be used for a purpose such as public safety, or the like.

When UE 1 plays a role of transmitting direct communication data, UE 1 transmits the direct communication data and UE 2 receives the direct communication data. Transmission and reception roles of UE 1 and UE 2 may be exchanged with each other. The direct communication transmission from UE 1 may be received by one or more UE(s) such as UE 2.

The D2D discovery and the D2D communication may not be associated with each other but independently defined. That is, in groupcast and broadcast direct communication, the D2D discovery is not required. As such, when the D2D discovery and the D2D direct communication are independently defined, the UEs need not recognize adjacent UE. In other words, in the case of the groupcast and broadcast direct communication, all receiving UEs in a group are not required to be proximate to each other.

As a channel for transmitting the D2D direct communication data, a physical sidelink shared channel (PSSCH) may be defined. Further, as a channel for transmitting control information (e.g., scheduling assignment (SA), a transmission format, and the like for transmitting the direct communication data) for the D2D direct communication, a physical sidelink control channel (PSCCH) may be defined. As the structures of the PSSCH and the PSCCH, the PUSCH structure may be reused.

As a resource allocation method for the D2D direct communication, two modes (mode 1 and mode 2) may be used.

Mode 1 represents a scheme in which the base station schedules a resource used for transmitting data or control information for the D2D direct communication to the UE. In the in-coverage, mode 1 is applied.

The base station configures the resource pool required for the D2D direct communication. Herein, the resource pool required for the D2D communication may be divided into a control information pool and a D2D data pool. When the base station schedules control information and D2D data transmission resources within a pool configured for transmitting D2D UE by using the PDCCH or ePDCCH, the transmitting D2D UE transmits control information and D2D data by using an allocated resource.

The transmitting UE requests a transmission resource to the base station and the base station schedules resources for transmitting the control information and the D2D direct communication data. That is, in the case of mode 1, the transmitting UE needs to be in the RRC_CONNECTED state in order to perform the D2D direct communication. The transmitting UE transmits the scheduling request to the base station and thereafter, the buffer status report (BSR) procedure is performed so that the base station determines the quantity of resources requested by the transmitting UE.

When receiving UEs monitor the control information pool and decodes control information associated therewith, the receiving UEs may selectively decode D2D data transmission associated with the corresponding control information. The receiving UE may not decode the D2D data pool according to a control information decoding result.

Mode 2 represents a scheme in which the UE arbitrarily selects a specific resource in the resource pool in order to transmit data or control information for the D2D direct communication. In the out-of-coverage and/or edge-of-coverage, mode 2 is applied.

In mode 2, the resource pool for transmitting the control information and/or the resource pool for transmitting the D2D direct communication data may be pre-configured or semi-statically configured. The UE receives the configured resource pool (a time and a frequency) and selects the resource for the D2D communication transmission. That is, the UE may select the resource for transmitting the control information in the control information resource pool in order to transmit the control information. Further, the UE may select the resource in the data resource pool in order to transmit the D2D direct communication data.

In D2D broadcast communication, the control information is transmitted by a broadcasting UE. The control information indicates explicitly and/or implicitly a position of a resource for data reception in association with the physical channel (that is, PSSCH) transporting the D2D direct communication data.

3) Synchronization

A D2D synchronization signal/sequence (D2DSS) may be used for the UE to acquire time-frequency synchronization. In particular, since the control of the base station is impossible out of the network coverage, a new signal and a new procedure for establishing UE-to-UE synchronization may be defined. The D2D synchronization signal/sequence (D2DSS) may be referred to as a sidelink synchronization signal.

A UE that periodically transmits the D2D synchronization signal/sequence (D2DSS) may be referred to as a D2D synchronization source or a sidelink synchronization source. When the D2D synchronization source is the base station, a structure of the D2D synchronization signal/sequence (D2DSS) may be the same as the PSS/SSS. When the D2D synchronization source is not the base station (for example, the UE or a global navigation satellite system (GNSS)), the structure of the D2D synchronization signal/sequence (D2DSS) may be newly defined.

The D2D synchronization signal/sequence (D2DSS) is periodically transmitted with a period which is not smaller than 40 ms. Each UE may have multiple physical-layer D2D synchronization identities. The physical-layer D2D synchronization identity may be referred to as a physical-layer sidelink synchronization identity or just referred to as a D2D synchronization identity.

The D2D synchronization signal/sequence (D2DSS) includes a D2D primary synchronization signal/sequence and a D2D secondary synchronization signal/sequence. The D2D primary synchronization signal/sequence and the D2D secondary synchronization signal/sequence may be referred to as a primary sidelink synchronization signal and a secondary sidelink synchronization signal, respectively.

Before transmitting the D2D synchronization signal/sequence (D2DSS), the UE may first search the D2D synchronization source. In addition, when the D2D synchronization source is searched, the UE may acquire the time-frequency synchronization through the D2D synchronization signal/sequence received from the searched D2D synchronization source. In addition, the corresponding UE may transmit the D2D synchronization signal/sequence.

Further, a channel may be required, which is used for purpose of transferring required information used for the UE-to-UE communication together with synchronization and the channel for the purpose may be defined. The channel may be referred to as a physical D2D synchronization channel (PD2DSCH) or a physical sidelink broadcast channel (PSBCH).

Hereinafter, direct communication between two devices in the D2D communication is described as an example for clarity, but the scope of the present invention is not limited thereto and the same principle described in the present invention may be applied even to D2D communication among two or more plural devices.

D2D Discovery

Hereinafter, in the present patent, a signal (alternatively, message) which the UEs periodically transmit for the D2D discovery may be referred to as the discovery message, the discovery signal, a beacon, and the like. Hereinafter, the discovery message, the discovery signal, the beacon, and the like are collectively called the discovery message.

In distributed discovery, as a resource used for the UE to transmit and receive the discovery message, a dedicated resource may be periodically allocated apart from a cellular resource. The dedicated resource will be described below with reference to FIG. 13.

FIG. 13 is a diagram for describing a distributed discovery resource allocating method in the wireless communication system to which the present invention can be applied.

Referring to FIG. 13, in a distributed discovery scheme, a discovery subframe (that is, a ‘discovery resource pool’) 1301 for discovery among all cellular uplink frequency-time resources is fixedly (alternatively, dedicatedly) allocated and the residual area is constituted by an LTE uplink wide area network (WAN) subframe area 1302 in the related art. The discovery resource pool may be constituted by one or more subframes.

The discovery resource pool may be periodically allocated at a predetermined time interval (that is, a ‘discovery period’). Further, the discovery resource pool may be repeatedly configured within one discovery period.

FIG. 13 illustrates an example in which the discovery resource pool is allocated with a discovery period of 10 sec and 64 consecutive subframes are allocated to the respective discovery resource pools. However, the size of the time/frequency resource of the discovery period and the discovery resource pool corresponds to one example and the present invention is not limited thereto.

The UE autonomously selects the resource (that is, the ‘discovery resource’) for transmitting the discovery message thereof in the dedicatedly allocated discovery pool and transmits the discovery message through the selected resource. This will be described below with reference to FIG. 14.

FIG. 14 is a diagram schematically illustrating a discovery process of a terminal using the distributed discovery resource allocating method in the wireless communication system to which the present invention can be applied.

Referring to FIGS. 13 and 14, the discovery scheme is largely constituted by three procedures of sensing a resource for transmitting the discovery message (S1401), selecting the resource for transmitting the discovery message (S1402), and transmitting and receiving the discovery message (S1403).

First, in sensing the resource for transmitting the discovery message (S1401), all UEs that perform the D2D discovery receive (that is, sense) all discovery messages during one period (that is, discovery resource pool) of the D2D discovery resource by a distributed scheme (that is, autonomously). For example, in FIG. 13, assumed that an uplink bandwidth is 10 MHz, all UEs receive (that is, sense) all discovery messages transmitted in N=44 RB (since a whole uplink bandwidth is 10 MHz, 6 RBs are used for PUCCH transmission in a total of 50 RBs.) for K=64 msec (64 subframes).

In addition, in selecting the resource for transmitting the discovery message (S1402), the UE classifies resources at a low energy level among the sensed resources and randomly selects the discovery resource among the classified resources within a predetermined range (e.g., lower x % (x=a predetermined integer, 5, 7, 10, . . . )).

The discovery resource may be constituted by one or more resource blocks having the same size and multiplexed by TDM and/or FDM in the discovery resource pool.

The reason why the UE selects the resource at the low energy level as the discovery resource is that the case of selecting the resource at the low energy level may be interpreted as a meaning that the UEs do not generally use the same D2D discovery resource nearby. That is, this disproves that there are not a lot of UEs that perform the D2D discovery procedure which causes interference nearby. Accordingly, there is a high possibility that the interference will be small at the time of transmitting the discovery message when the resource at the low energy level is selected.

Further, the reason for randomly selecting the discovery resource within the predetermined range without selecting a resource at a lowest energy level is that there is a possibility that several UEs will simultaneously select the same resource corresponding to the lowest energy level when selecting the resource at the lowest energy level. That is, the same resource at the lowest energy level is selected, and as a result, the interference may be frequently caused. Therefore, the corresponding resource is preferably randomly selected within a predetermined range (that is, configuring a candidate pool of selectable resources). Herein, for example, a range of the energy level may be variably set according to a design of a D2D system.

In addition, in transmitting and receiving the discovery message (S1403) as a last procedure, the UE transmits/receives the discovery message based on the discovery resource selected after one discovery period (after P=10 sec in the example of FIG. 13) and periodically transmits/receives the discovery message according to a random resource hopping pattern at subsequent discovery periods.

The D2D discovery procedure is performed even in the RRC_CONNECTED state in which the UE and the base station are connected and continuously performed even in the RRC_IDLE state in which the UE and the base station are not connected.

When such a discovery scheme is considered, all UEs sense all resources (that is, the discovery resource pool) which adjacent UEs transmit and randomly select the discovery resource among the sensed resources within the predetermined range (e.g., within the lower x %).

D2D Direct Communication

Hereinafter, methods for transmitting/receiving D2D control information and/or D2D data proposed in the specification will be described in detail.

The D2D control information may be referred to as sidelink control information (SCI) or scheduling assignment (SA). As described above, the D2D control information may be transmitted on the PSCCH and the D2D data may be transmitted on the PSSCH. Hereinafter, the D2D control information will be referred to as SA.

FIG. 15 is a diagram for describing a method for transmitting/receiving signaling for D2D direct communication in the wireless communication system to which the present invention can be applied.

FIG. 15 illustrates a method that performs the D2D communication by transmitting/receiving a D2D operating procedure in a D2D operating procedure (D2D communication Mode 1) by the control of the base station and information associated therewith.

As illustrated in FIG. 15, a scheduling assignment (SA) resource pool 1510 and/or a data resource pool 1520 associated with the D2D communication may be pre-configured and the pre-configured resource pool may be transmitted from the base station to the D2D UEs through the high layer signaling.

The high layer signaling may be the RRC signaling.

An expression of ‘A and/or B’ used in the specification may be interpreted as a concept meaning at least one of A and B (indicating A, B, or A & B).

The SA resource pool and/or data resource pool means a resource reserved for the D2D (UE-to-UE) link or the D2D communication.

The UE-to-UE link may be expressed as sidelink.

In detail, the SA resource pool means a resource area to transmit the SA and the data resource pool means a resource area to transmit the D2D data.

The SA may be transmitted according to an SA period 1530 and the D2D data may be transmitted according to a data transmission period 1540.

The SA period and/or the data transmission period may be transmitted from the base station to the D2D UE through a D2D grant.

Alternatively, the SA period may be transmitted through the D2D grant and the data transmission period may be transmitted through the SA.

Herein, the D2D grant represents downlink control information (DCI) required for transmitting the SA and the D2D data transmitted to the D2D UE by the base station.

The D2D grant may be expressed as DCI format 5 and transmitted through the physical layer channels including the PDCCH, the EPDCCH, and the like or an MAC layer channel.

Further, the D2D grant may include information associated with SA transmission and information associated with data transmission.

The SA may include a resource allocation (RA), an MCS, a new data indicator (NDI), a redundancy version (RV), and the like as an example.

As described above, the SA resource pool for the SA transmission may be transmitted through the RRC signaling.

Further, the SA may be transmitted through the Physical Sidelink Control Channel (PSCCH) and the D2D data may be transmitted through the Physical Sidelink Shared Channel (PSSCH).

The D2D transmitting UE may receive SA information, in particular, resource allocation (RA) information (hereinafter, referred to as ‘SA RA’ information) in which the SA may be transmitted, from the base station through the D2D grant.

In this case, the D2D transmitting UE may transmit the SA RA information received from the base station to the D2D receiving UE as it is or generate new SA RA information by referring to the received SA RA information and thereafter, transmit the newly generated SA RA information to the D2D receiving UE.

Herein, when the D2D transmitting UE newly generates the SA RA, the D2D transmitting UE needs to perform resource allocation of the SA only within the resource pool indicated by a D2D grant RA.

That is, the D2D transmitting UE may transmit the SA by selecting only a partial resource area (SA RA) in the resource area (D2D grant RA) which eNB allows to be used.

Alternatively, contrary to this, the D2D transmitting UE may use the D2D grant RA allocated by the eNB as it is.

FIG. 16 is a diagram for describing a method for transmitting downlink control information for D2D direct communication in the wireless communication system to which the present invention can be applied.

First, the SA resource pool and/or D2D data resource pool associated with the D2D communication are/is configured by a high layer (S1610).

Thereafter, the base station transmits the SA resource pool and/or D2D data resource pool to the D2D UE through the high layer signaling (S1620).

Thereafter, the base station transmits control information associated with the SA and/or control information associated with the D2D data to the D2D transmitting UE through the D2D grant separately or together (S1630). The control information includes scheduling information of the SA and/or D2D data in the SA resource pool and/or D2D data resource pool. The control information may include the RA, the MCS, the NDI, the RV, and the like as one example.

Thereafter, the D2D transmitting UE transmits the SA and/or D2D data to the D2D receiving UE based on the information received in step S1630 (S1640).

The SA transmission and the D2D data transmission may be simultaneously performed or the D2D data may be transmitted after the SA is transmitted.

Meanwhile, although not illustrated in FIG. 16, the D2D transmitting UE requests a transmission resource (that is, a PSSCH resource) for the D2D data to the base station and the base station schedules resources for transmitting the SA and the D2D data. To this end, the buffer status report (BSR) procedure may be performed so that the D2D transmitting UE transmits the scheduling request (SR) to the base station and thereafter, the base station determines the quantity of resources requested by the D2D transmitting UE.

Herein, Since the SR is the SR for requesting allocation of not the PUSCH resource but the PSSCH resource, the SR may be distinguished from the SR for requesting the PUSCH resource. To this end, in order to distinguish the SR for the PSSCH from the SR for the PUSCH, a PUCCH resource index (that is, the PRB in which the SR is transmitted), a cyclic shift (CS) applied to the basic sequence (e.g., ZC sequence) for frequency domain spread of the SR, and an orthogonal code (OC) for time domain spread of the SR may be differently configured.

When the D2D Rx UEs monitor the control information pool and decodes control information associated therewith, the D2D Rx UEs may selectively decode D2D data transmission associated with the corresponding control information.

The D2D grant serves to allocate the resources which the D2D Tx UE requires for transmitting the SA and the data and transfer the control information including the MCS, and the like, that is, the scheduling information, as described above.

Further, since the SCI is used for scheduling the PSSCH from the viewpoints of the D2D Tx UE and the D2D Rx UE, a DCI format for the D2D grant proposed in the present invention may be used for scheduling the PSSCH and include field information of the SCI.

The DCI format for the D2D grant (alternatively, the sidelink grant) includes both the scheduling for the SA and the data as described above, but a resource allocation assignment/allocation (RA) field (alternatively, information) for the SA and an RA field (alternatively, information) for the data may be distinguished from each other.

For example, the DCI format for the D2D grant may be constituted by a frequency hopping flag (FH) field, a resource allocation (RA) field for the D2D SA, a first RA field for the D2D data, a second RA field for the D2D data, a TPC field, and a zero padding (ZP) bit(s) (a case in which the ZP bit(s) is(are) present).

The FH field indicates whether frequency hopping is applied at the time of transmitting the SA and the data. Since the FH field may be commonly applied to the SA transmission and the data transmission, the FH field may be constituted by one field.

For example, when an FH field value is ‘1’, the D2D Tx UE performs frequency hopping transmission at the time of transmitting the SA and the data and when the FH field value is ‘0’, the D2D Tx UE does not perform the frequency hopping transmission at the time of transmitting the SA and the data.

The SA RA field (alternatively, a PSCCH RA field, a resource field for the PSCCH) indicates resource information for the SA transmission. That is, the SA RA field indicates scheduling information (that is, resource information) for PSCCH transmission. Therefore, the D2D Tx UE transmits the SA (that is, the PSCCH) in a resource indicated by the SA RA field.

Herein, the SA RA field may also include information (alternatively, an index) for deriving a time for the SA transmission and/or a position of the frequency resource area.

For example, the SA RA field may announce a start position (that is, the index) of the resource for the SA transmission. In other words, the SA RA field may indicate a start index of a subframe and/or a resource block in which the SA is transmitted.

Further, the D2D Tx UE may derive a time resource (e.g., a subframe index) and/or a frequency resource (e.g., a resource block index) for the SA transmission by using a predetermined function (equation) based on the information included in the SA RA field.

The resource allocation information for the D2D data transmission may be constituted by a D2D data first RA field (alternatively, a first PSSCH RA field, a resource block allocation and hopping resource allocation field), a D2D data second RA field (alternatively, a second PSSCH RA field, a time resource pattern field).

The D2D data first RA field indicates the resource information (e.g., the resource block) for the D2D data transmission in the frequency domain. That is, the D2D data first RA field indicates the scheduling information in the frequency domain for the PSSCH transmission. Therefore, the D2D Tx UE transmits the D2D data (that is, the PSSCH) in a frequency resource indicated by the D2D data first RA field.

For example, the D2D data first RA field may indicate a start position (that is, a start resource block index) of the resource block for the D2D data transmission and the length of the allocated resource block by using a resource indication value (RIV) like a UL RA scheme.

Further, the D2D data first RA field may separately and announce the start position (that is, the start resource block index) and an end position (that is, a last resource block index) of the resource block for the D2D data transmission as separate fields (alternatively, information). In this case, an additional bit (e.g., 1 bit) may be further required.

The D2D data second RA field indicates resource information (e.g., the subframe) used for the D2D data transmission in the time domain. That is, the D2D data second RA field indicates the scheduling information in the time domain for the PSSCH transmission. Therefore, the D2D Tx UE transmits the D2D data (that is, the PSSCH) in a time resource indicated by the D2D data first RA field.

For example, the D2D data second RA field may indicate a subframe pattern (that is, a time resource pattern) to be used for the D2D data transmission. That is, the D2D data second RA field may include information indicating the time resource pattern used for the PSCCH transmission.

Herein, the D2D data second RA field may indicate any one pattern of a plurality of predetermined time resource patterns. For example, n subframe patterns (expressed by a bitmap) may be pre-defined like SF pattern #0(10001010), SF pattern #1(00111001), . . . , SF pattern #n(10011001) and the D2D data second RA field may indicate any one subframe pattern of n defined subframe patterns. Herein, a value of ‘1’ of the bitmap may mean that the D2D data is transmitted in a corresponding subframe and a value of ‘0’ may mean that the D2D data is not transmitted in the corresponding subframe. Further, the values of the bitmap may have meanings contrary thereto.

A TPC field indicates transmission power for the SA and data transmission in the D2D Tx UE. That is, the TPC field indicates transmission power information of the PSCCH and the PSSCH.

The TPC field 4205 may be constituted by one field. As such, when the TPC field is constituted by one field, the TPC field value is commonly applied to the transmission power for the SA transmission and the transmission power for the data transmission.

The ZP may be filled with the control information, not used, or not present as necessary. That is, when the ZP is not required, the ZP may be omitted.

Each field order and a bit count of each bit of the DCI format exemplified as above are just one example for easy description and may be modified.

Meanwhile, as compared with DCI format 0 given above, the DCI format for the D2D grant exemplified as above does not include the MCS field.

When the eNB announces the MCS value to the D2D Tx UE, the MCS field needs to be present in the DCI format for the D2D grant. However, the D2D Tx UE may autonomously determine the MCS value or the MCS value may be transferred through the higher layer signaling (e.g., the RRC signaling) or determined as a pre-fixed value. Accordingly, the D2D grant does not include the MCS field.

Further, the DCI format for the D2D grant exemplified as above does not include even the NDI field and the RV field. Similarly to the above, the D2D Tx UE may autonomously determine the NDI and RV values or the NDI and RV values may be transferred through the higher layer signaling (e.g., the RRC signaling) or determined as pre-fixed values.

Method for Measuring Position of D2D UE

FIG. 17 is a diagram illustrating a scenario of measuring a position of UE using a D2D signal/channel according to an embodiment of the present invention.

The present invention proposes a method in which UE measures a position of a counterpart UE or a distance between the counterpart UE and the UE by using signals used to transmitting/receiving a D2D direct radio channel/signal to/from another UE as illustrated in FIG. 17.

If the UE may determine the position of another UE or a distance from another UE, the UE may provide various useful services. As one example, if the UE may determine a distance from UE of another user registered as a friend of a user, when the corresponding friend is positioned within a predetermined distance, the UE may provide a service that announces the fact to the user to determine who is a friend positioned close to the user. As another example, when multiple UEs transmit a message such as the advertisement, the user may enable an operation that configures only an advertisement message which is present within a predetermined distance from the UE of the user to be received. As yet another example, the UE may provide a service that observes whether UE registered as an interest target therein is present within a predetermined area therefrom or a distance therefrom and announces whether the UE registered as an interest target therein is present within a predetermined area therefrom or the distance therefrom to the user.

A technology that determines positional information of the UE in the wireless communication system includes a series of technologies in which the UE receives the signal transmitted by the eNB and determines the position thereof based on the received signal.

In the technology, the UE measures an arrival time of a transmitted signal from each eNB with respect to a plurality of eNBs by measuring the signal (a positioning reference signal (PRS)) transmitted by the eNB or a difference between arrival times of transmitted signals from two eNBs to determine the position of the UE.

When a more detailed principle is described, when the UE measures the difference between the arrival times of the transmitted signals from two eNBs, the UE may determine a distance between distances from two corresponding eNBs. In addition, the distance between the distances from two eNBs may indicate that the UE is positioned at one point on a certain curve. When such a process is repeatedly applied even to two other eNBs, various curves at which the UE may be positioned and it may be determined that the UE is positioned at a point where the curves meet.

When the positional information of the eNB which is measured by the UE is actually required for such an operation and when the UE reports the arrival time of the transmitted signal from the eNB or the difference between the arrival times of the transmitted signals from two eNBs, which are described above to the network, the network has already known which eNB is positioned and where the eNB is positioned, the network may determine the position of the corresponding UE.

Another technology that determines the positional information of the UE in the wireless communication system includes a series of technologies in which the eNB receives the signal transmitted by the UE and the network determines the position of the corresponding UE based on the received signal.

In the technology, the UE transmits a specific signal (a sounding reference signal of the 3GPP LTE/LTE-A) and while the plurality of eNBs receives the transmitted signal, the arrival time of the transmitted signal from the UE or a difference between arrival times of transmitted signals in two eNBs from the UE is measured. Then, the network may calculate a distance from the UE in each eNB or a difference between distances from the corresponding UE in two eNBs based on the positional information of each eNB and determine a point where the operation is repeatedly commonly shown with respect to various eNBs as a point where the corresponding UE is positioned.

However, the aforementioned operations for measuring the position of the UE in the related art may be inappropriate to be widely used when one UE intends to determine the position of another specific UE. First, since the network finally determines the position of the UE in both schemes, if specific UE intends to use the positional information of another UE, the network needs to measure the position through a series of operations with UE as a target of which the position is measured and thereafter, transfer the corresponding information to UE which desires the measured position. During such a process, signaling overhead occurs between the network and the UE and when the number of UEs significantly increases, calculation complexity for the network to calculate the position of every UE significantly increases. In particular, when the information desired by the UE corresponds to an accurate position of the target UE but partial information such as the distance from the UE, there is a high possibility that the signaling overhead or the calculation complexity will acts as unnecessary cost.

In order to solve the problem, the present invention proposes a scheme that measures the positions of the UEs and the distance between the UEs, which minimizes the signaling overhead and the calculation complexity from the viewpoint of the network by transmitting/receiving the direct D2D channel/signal (e.g., the PDSCH, the PSBCH, the D2D synchronization signal, the D2D reference signal, and the like) between the UE and the UE.

Hereinafter, in the present invention, it is assumed that each UE transmits a signal announcing presence thereof according to a predetermined rule. For example, the signal may correspond to the discovery signal/message (that is, the PSDCH), the D2D synchronization signal, a D2D broadcast channel (that is, the PSBCH), the D2D reference signal, and the like and hereinafter, the signals will be collectively called and described as the discovery signal (DS).

UE that receives a specific DS according to a rule of DS transmission is designed to determine who the UE transmitting the DS is. As one example, the DS may include the identity information of the transmitting UE.

Herein, the DS transmission rule includes a method in which each UE generates the DS and a method for generating the time/frequency resource that transmits the DS described as above.

The network may operate to allow UEs that participate in DS transmission/reception to determine the rule by transmitting (e.g., a broadcast scheme) the DS transmission rule through the system information (e.g., a master information block (MIB) or the system information block (SIB)) or the high layer signal such as the RRC signaling.

In the present invention, the UE assumes that the eNB which becomes a criterion for determining a transmission time is present at the time of transmitting the DS. This is referred to as DS reference eNB.

The UE may have a plurality of DS reference eNBs. For example, the UE may operate to transmit the DS with eNB1 as the DS reference eNB at time 1 and transmit the DS with eNB1 as the DS reference eNB at time 2.

Hereinafter, in the specification, UE that intends to measure the position of another UE by receiving the DS will be named as ‘operation UE’ and UE of which position the operation UE intends to measure will be referred to as ‘target UE’. That is, the operation UE measures the DS transmitted by the target UE to measure the position of the target UE or a distance between the operation UE and the target UE.

FIG. 18 is a diagram for describing a spread delay between UEs according to an embodiment of the present invention.

FIG. 18 illustrates the time when the target UE transmits the DS and the time when the operation UE receives the DS.

When eNB_(n) is given as the DS reference eNB, the target UE determines a transmission time of the DS from a time when the target UE receives a DL subframe boundary of the eNB_(n).

When the eNB_(n) transmits the DL subframe boundary at a time t_(n) and a propagation delay between the eNB_(n) and the target UE is k_(n), a time when the target UE receives the DL subframe boundary of the eNB_(n) becomes ‘t_(n)+k_(n)’.

At this time, the target UE transmits the DS thereof at a time earlier by a time as long as F_(n) and the F_(n) value may be a pre-fixed value or given by an indication of the eNB. If the F_(n) value is pre-fixed, the F_(n) value may be fixed as the same value with respect to all DS reference eNBs.

A time when a signal which the target UE transmits at a time ‘t_(n)+k_(n)−F_(n)’ reaches the operation UE through the propagation delay ‘x’ between the target UE and the operation UE may be expressed as shown in Equation 1 given below. u _(n) =t _(n) +k _(n) −F _(n) +x  [Equation 1]

A propagation delay between DS reference eNB_(n) and the operation UE is assumed as d_(n).

Hereinafter, a method for acquiring an upperlimit and a lowerlimit of the distance between the operation UE and the target UE when the DS is transmitted by the aforementioned process will be described.

FIGS. 19 and 20 are diagrams for describing a method of measuring a distance between operating UE and target UE by using a D2D signal/channel according to an embodiment of the present invention.

First, in the case of x≤d_(n), an area where the target UE may be positioned is illustrated in FIG. 19.

A maximum value and a minimum value of the time when the operation UE receives the DS of the target UE are shown in target UE position 1 1901 and target UE position 2 1902, respectively.

When the target UE is positioned at position 1 1901, the time when the operation UE receives the DS of the target UE may be shown in Equation 2 given below. u _(n) ≤t _(n) +d _(n) +x−F _(n) +x=t _(n) +d _(n) −F _(n)+2x  [Equation 2]

That is, when k_(n)=d_(n)+x is applied to Equation 1 given above, a result shown in Equation 2 is derived.

Herein, a condition of x≥(u_(n)+F_(n)−t_(n)−d_(n))/2 is acquired.

Further, when the target UE is positioned at position 2 1902, the time when the operation UE receives the DS of the target UE may be shown in Equation 3 given below. u _(n) ≥t _(n) +d _(n) −x−F _(n) +x=t _(n) +d _(n) −F _(n)  [Equation 3]

That is, when k_(n)=d_(n)−x is applied to Equation 1 given above, a result shown in Equation 3 is derived.

When the target UE is positioned at position 2 1902, the time when the operation UE receives the DS of the target UE acquires a condition regardless of x.

Meanwhile, in the case of x>d_(n), the area where the target UE may be positioned is illustrated in FIG. 20.

The maximum value and the minimum value of the time when the operation UE receives the DS of the target UE are shown in target UE position 1 2001 and target UE position 2 2002, respectively.

When the target UE is positioned at position 1 2001, the time when the operation UE receives the DS of the target UE may be shown in Equation 4 given below. u _(n) ≤t _(n) +d _(n) +x−F _(n) +x=t _(n) +d _(n) −F _(n)+2x  [Equation 4]

That is, when k_(n)=d_(n)+x is applied to Equation 1 given above, a result shown in Equation 4 is derived.

In this case, the same condition as the case of Equation given above is acquired.

Further, when the target UE is positioned at position 2 2002, the time when the operation UE receives the DS of the target UE may be shown in Equation 5 given below. u _(n) ≥t _(n) +x−d _(n) −F _(n) +x=t _(n) −d _(n) −F _(n)+2x  [Equation 5]

That is, when k_(n)=d_(n)−x is applied to Equation 1 given above, a result shown in Equation 5 is derived.

Herein, a condition of x≤(u_(n)+F_(n)−t_(n)+d_(n))/2 is acquired.

When the above calculated result is summarized, the propagation delay ‘x’ between the operation UE and the target UE satisfies a condition shown in Equation 6 given below.

$\begin{matrix} {\frac{u_{n} + F_{n} - \left( {t_{n} + d_{n}} \right)}{2} \leq {\times {\leq \frac{u_{n} + F_{n} - \left( {t_{n} - d_{n}} \right)}{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 6} \right\rbrack \end{matrix}$

In Equation 6, since ‘u_(n)’ is the time when the operation UE receives the DS transmitted by the target UE, ‘u_(n)’ may be measured by the operation UE.

Since ‘t_(n)+d_(n)’ is the time when the operation UE receives the downlink subframe boundary of the eNB_(n), ‘t_(n)+d_(n)’ may be measured.

If F_(n) is a predetermined value, F_(n) is a value which the operation UE has already known or if F_(n) is a value indicated by the eNB, the eNB may transfer the value or the target UE may directly announce the value to the operation UE. For example, F_(n) may be transferred by using a partial field of the DS.

The operation UE determines d_(n) based on a measurement value of ‘t_(n)+d_(n)’ to calculate ‘t_(n)d_(n)’. For example, the operation UE may attempt a random access to the DS reference eNB_(n) and in this case, a timing advance value announced by the eNB_(n) may be regarded as a round trip delay with the operation UE and the eNB_(n), that is, 2*d_(n). Further, the operation UE may acquire d_(n) from a signal (e.g., a cell reference signal (CRS), a demodulation reference signal (DMRS), a channel state information-RS (CSI-RS), a PRS, and the like) transmitted by the DS reference eNB.

According to the aforementioned operation, the operation UE may determine the upperlimit and the lowerlimit for the propagation delay ‘x’ with the target UE. Since the determined upperlimit and lowerlimit have different values with respect to different DS reference eNBs, the operation UE first calculates the upperlimit and the lowerlimit of x with respect to each DS reference eNB and thereafter, sets an intersection for areas of a plurality of calculated x to narrow a range of the area where x is present.

When information on the propagation delay ‘x’ with the operation UE and the target UE is acquired, the information is multiplied by a progress speed of an electromagnetic wave to be converted into the distance between the operation UE and the target UE.

Hereinafter, a method for measuring the position of the target UE by using the positional information of the DS reference eNB and the DS receiving time will be described.

FIGS. 21 and 24 are diagrams for describing a method of measuring a position of the target UE by using the D2D signal/channel according to an embodiment of the present invention.

As described in FIG. 18 as above, since u_(n)=t_(n)+k_(n)−F_(n)+x is given, the case where the operation UE receives the DSs transmitted by the target UE is received at the same time at two different points means, that is to say, that ‘k_(n)+x’s calculated from two points have the same value (since t_(n) and F_(n) are constant). Herein, since ‘k_(n)+x’ means the spread delay of the signal which reaches the operation UE from the DS reference eNB_(n) through the target UE, the position of the target UE which makes the same u_(n) shows an oval shape having the positions of the DS reference eNB_(n) and the operation UE as a focus as illustrated in FIG. 21.

That is, when the operation UE measures u_(n) and calculates k_(n)+x based on the measured u_(n), the operation UE may find that one oval is formed and the target UE is positioned at any point on the corresponding oval.

In FIG. 22, it may be determined that the ovals are formed with respect to two DS reference eNBs and the target UE may be present at positions 2201 and 2202 corresponding to intersection points of two ovals according to a principle described in FIG. 21.

In addition, FIG. 23 corresponds to a case where the operation is repeated with respect to three DS reference eNBs. Since an intersection point of three ovals is expressed as a single point 2301, the position of the target UE may be fixed as one.

In FIGS. 22 and 23, a_(nm) represents a distance between DS reference eNB_(n) and eNB_(m).

As described above, the oval where the target UE may be positioned is formed with respect to two or more DS reference eNBs, and as a result, the operation UE requires information on the position of each DS reference eNB in order to determine the position of the target UE. The network may transmit the information on the position of each DS reference eNB to the UE through the system information (e.g., the master information block (MIB) or the system information block (SIB) or the high layer signal such as the RRC signaling, or the like (e.g., a broadcast scheme) and announce the information to the UE in advance.

The positional information of the DS reference eNB may be expressed as a form of an absolute coordinate such as a longitude and a latitude of each eNB and in this case, the operation UE may determine the absolute coordinate of the target UE by applying the described principle.

On the contrary, when not the position of the target UE but the distance between the target UE and the operation UE is measured, the absolute coordinate of the DS reference eNB is not required but only a relative position is required. In this case, for example, only information on a distance between the DS reference eNBs may be provided to the operation UE.

Referring to FIG. 23, when the target UE acquires information on the distance (a_(nm)) between the DS reference eNB_(n) and the eNB_(m), the relative position of the respective eNBs may be determined and the relative position of the operation UE may also be determined by applying the principle based on the relative position of the respective eNBs.

The operation UE needs to determine the distance from each DS reference eNB even by such a scheme and the distance may be determined from the timing advance value acquired during the random access process as described above. Further, the operation UE may acquire d_(n) from the signal (e.g., the CRS, the DMRS, the CSI-RS, the PRS, and the like) transmitted by each DS reference eNB.

Meanwhile, when the operation UE may find the distance between the target UE and the DS reference eNB, the distance also assists measuring the distance from the target UE or determining the position of the target UE.

For example, it is assumed that the network announces a distance between the target UE and specific DS reference eNB to the operation UE or the target UE announces the distance between the target UE and the specific DS reference eNB to the operation UE by using the D2D signal (e.g., by using some bits of the DS).

In this case, the operation UE may determine a candidate position of the target UE from the DS transmitted by the target UE based on the corresponding DS reference eNB according to the principle described in FIG. 21 given above and herein, a circle corresponding to the distance between the corresponding DS reference eNB and the target UE is added to the determined candidate position as illustrated in FIG. 24 to reduce the candidate position of the target UE.

Hereinafter, a method for measuring the position of the target UE or the distance from the target UE by using a difference in reception time of the DS signal will be described.

FIGS. 25 and 26 are diagrams for describing a method of measuring the position of the target UE or the distance from the target UE by using the D2D signal/channel according to an embodiment of the present invention.

Since u_(n)=t_(n)+k_(n)−F_(n)+x is given as described in FIG. 18, if the operation UE measures u_(n) and u_(m) with respect to the DSs which the target UE transmits based on eNB_(n) and eNB_(m) which are two DS reference eNBs, respectively, distances between the target UE and two DS reference eNBs may be determined due to a difference between two values.

In more detail, the difference between u_(n) and u_(m) becomes u_(n)−u_(m)=t_(n)−t_(m)+k_(n)−k_(m)−F_(n)+F_(m) and herein, the distance x between the target UE and the operation UE which is a common element disappears.

As described above, the operation UE determines F_(n) and F_(m) or for easy operation, two values may be similarly described and in this case, two components disappear.

Information on t_(n) and t_(m) may be derived from time information (e.g., the radio frame and subframe indexes) when the target UE transmits the DS based on each DS reference eNB and it may be assumed that the DS reference eNB is synchronized by a time unit (e.g., the unit of 1 ms configuring the subframe) at a predetermined level or less. That is, assumed that two DS reference eNBs are synchronized by the unit of 1 ms, the operation UE may assume that the DL subframe boundaries transmitted by two DS reference eNBs correspond to the same time.

According to the operation, the operation UE may calculate k_(n)−k_(m) corresponding to the difference in distance between the target UE and the DS reference eNB from u_(n)u_(m).

A curve representing a candidate area where the target UE may be positioned may be formed based no the positional information of two DS reference eNBs as illustrated in FIG. 25 based on k_(n)−k_(m). That is, the curve is represented by a set of points where the difference between the distances from two DS reference eNBs is constantly given.

When the operation is performed with respect to a combination of two other eNBs, another curve may be formed and an intersection point of two curves becomes the position of the target UE. FIG. 26 corresponds to a case where the operation is additionally performed with respect to eNB2 and eNB3.

Similarly eve in the scheme, the operation UE needs to determine the distance from each DS reference eNB and the distance may be determined from the timing advance value acquired during the random access process as described above. Further, the operation UE may acquire d_(n) from the signal (e.g., the CRS, the DMRS, the CSI-RS, the PRS, and the like) transmitted by each DS reference eNB.

D2D UE Group Managing Method

The present invention proposes a method for efficiently maintaining or managing the group as a plurality of D2D UEs forms the group and manages group members based on specific D2D UE (e.g., a group leader) in the corresponding D2D group to transmit and receive an appropriate message for separation from the group and a service using the same. That is, the present invention proposes a technology that determines the positions of the respective group members by using the D2D signals including the D2D discovery signal (that is, the PSDCH), the D2D control channel (that is, the PSCCH), the D2D data channel (that is, the PSSCH), the D2D broadcast channel (that is, the PSBCH), the D2D synchronization signal, and the like and manages the group and a service to which the technology may be applied.

For example, it is assumed that a teacher (a group representative, a group leader, and the like) performs outdoor activities together with students (group members except for the teacher). It is assumed that if necessary, the leader in the group may become anyone of the members in the group and changed as necessary and the outdoor activities include inside/outside activities and the group members may perform activities anywhere simultaneously indoors and outdoors. In this case, the teacher may continuously verify the positions of the students, bidirectionally communicate with the students in real time, and announce a range deviation warning to a counterpart. This will be described in more detail with reference to drawings given below.

Herein, in describing the present invention, even though detailed description of the method for transmitting the D2D discovery signal (that is, the PSDCH) or the D2D direct communication data is not mentioned, the aforementioned transmission method (in particular, the method according to FIGS. 11 to 16) may be similarly applied.

Further, in the specification, a D2D identifier (ID) may be an ID for distinguishing the D2D UE, an ID for distinguishing a specific application program of the UE, or all temporary allocated IDs valid only for a designated time.

FIG. 27 illustrates a user interface for implementing a D2D terminal group managing method according to an embodiment of the present invention.

FIG. 27(a) illustrates, a user interface for a group representative UE (UE A, e.g., a teacher's UE), a step of generating multiple UEs (e.g., UEs of high school students) stored in a contact history of UE A as the group and the group which may receive the D2D service. FIG. 27 illustrates a case in which group 1 and group 2 are stored in the contact history of UE A and group 2 is selected.

Further, the group may be generated by searching a name of a person (UEs B, C, D, E, F, and the like in FIG. 27) in contacts not stored as the group in order to add the member to the D2D group or directly receiving phone numbers not stored in the contact history of UE A from the user.

As such, the D2D group may be generated in UE A itself without approval (alternatively, permission) to the member which belongs to the corresponding group when the group is generated in UE A.

Further, contrary to this, a group request message for requesting the approval (alternatively, permission) may be transmitted to the member (e.g., UEs B, C, D, E, F, and the like) which belongs to the corresponding group when the group is generated in UE A. In addition, only UE that transmits a group response message as a response to the group request message may become the member of the D2D group generated in UE A.

When the generation of the D2D group is completed, positions 2702, 2705 a, 2705 b, and 2705 c of UEs which belong to the corresponding D2D group are displayed and tracked together with a position 2701 of UE A in UE A in real time as illustrated in FIG. 27(b). Further, not the positions 2702, 2705 a, 2705 b, and 2705 c of the UEs which belong to the D2D group but distances from UE A based on the position 2701 of UE A may be displayed.

Herein, the position 2701 of UE A, the positions 2702, 2705 a, 2705 b, and 2705 c of the UEs which belong to the D2D group, or the distances between UE A and the UEs which belong to the D2D group may be derived by using the methods described in FIGS. 17 to 26 given above. Further, the position 2701 of UE A, the positions 2702, 2705 a, 2705 b, and 2705 c of the UEs which belong to the D2D group, or the distances between UE A and the UEs which belong to the D2D group may be obtained by using a global positioning system (GPS).

Boundaries 2703 and 2704 representing a predetermined range may be configured based on the position of UE A and a plurality of boundaries may be configured according to purposes thereof. FIG. 27 illustrates a case where two boundaries are configured.

Herein, boundary 2 2704 may be configured as a maximum distance (e.g., 1 km) which may be covered by using the D2D technology or configured by a specific distance (e.g., 600 m) determined by the user (e.g., the teacher) of UE A. Further, boundary 1 2703 may be configured as a boundary of a specific area from which the group members should not deviate due to safety of the group members or specific other reasons. This case means a state (an excessive area to receive a warning message) in which group members (that is, B 2705 a, C 2705 b, and 2705 c) positioned between boundary 1 2703 and boundary 2 2704 are positioned out of coverage desired (that is, configured) by UE A. As illustrated in FIG. 27(b), UE A may automatically/manually transmit a warning to the group members (that is, B 2705 a, C 2705 b, and D 2705 c) which deviate from a predetermined area.

FIG. 27(c) illustrates a UI/user experience (UX) for UE B that receives the warning message or a notification message from UE A by using the D2D technology when UE B deviates from predetermined coverage. For example, UE A may transmit the warning message or notification message to UE B through the discovery message (that is, the PSDCH) or PSSCH.

Further, various services associated with the next action may be immediately connected together with the warning/notification message indicating that UE B deviates from the predetermined coverage. For example, a call may be connected from UE B to UE A, a text message (e.g., including positional information of UE B) is transmitted, or a path finding service from the position of UE B to UE A may be provided. Herein, a phone call/short message service (SNS) to UE A may be supported through the D2D communication (e.g., using the PSSCH) or a cellular network. The path finding service may also be supported through the D2D communication (e.g., using the PSSCH) or the cellular network and the path finding service may support UE B to go to the position where UE A is positioned by using a map, and the like.

In FIG. 27, a scenario in the open air is a representative example, but a scenario in which both the inside and outside activities are performed like a shopping mall may also be considered. In this case, when representative group UE or member UEs which belong to the group are positioned indoors, it is difficult to know an accurate distance by using the GPS and when an indoor position based service (LBS) such as a wireless local area network (WLAN), or the like is used, there is a difficulty in an accurate position of an access point (AP) needs to be secured in advance, and the like. In this case, the position measuring technology using the D2D discovery message, and the like, which is described in FIGS. 17 to 26 as above enables effectively securing the positional information of the UEs under any situation regardless of the inside/the outside based on stability which a cellular technology guarantees.

Which flow a related signal has in order to support the service of FIG. 27 will be described with reference to FIG. 27 given below.

FIG. 28 is a diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

Although not illustrated in FIG. 28, it is assumed that all group member UEs form a specific group like the example of FIG. 27 based on the D2D ID or another membership service in advance. Further, it is assumed that all UEs periodically or aperiodically broadcasts the D2D signal (e.g., the D2D discovery signal).

First, case 1 is described. In case 1, it is assumed that UE A is the representative group UE.

When a specific UE A user of the corresponding group needs to determine the positions of the group members while performing a personal activity, UE A executes an application by receiving an input from the user (S2801).

UE A receives the discovery signal periodically or aperiodically broadcasted from the group member UEs (e.g., a smart phone and a wearable device) positioned within D2D coverage (S2802).

As described above, the D2D UE periodically or aperiodically broadcasts the discovery signal. Therefore, in FIG. 28, it is illustrated that step S2802 is performed after step S2801 for easy description, but UE A continuously receives the discovery signal from the group member UE regardless of execution of the application (that is, regardless of step S2801).

Further, UE A continuously receives the discovery signal from adjacent D2D UE regardless of generation of the group. However, UE A may identify the discovery signal transmitted from the group member UE based on the UE identity ID (alternatively, the D2D ID) included in the discovery signal after the group is generated.

Further, although not illustrated in FIG. 28, UE A also periodically or aperiodically broadcasts the discovery signal.

In this case, UE A may calculate the distance between UE A and the group member UE or the position of the group member UE by using the methods described in FIGS. 17 to 26 given above based on the discovery signal received from the group member UE.

Further, the positions of the group member UEs including UE A may be displayed on the map like the example of FIG. 27(b) given above in order to conveniently support the UX.

As such, in order to display the positions of the group member UEs on the map, UE A transmits a map transmission request message to a map server (S2803) and receives map information from the map server (S2804).

In addition, UE A displays the map by using the received map information and displays the position of the group member UE on the map (S2805).

Herein, the map server may correspond to a communication operator or a service provider. As a result, UE A may display the received map information and display the positions of the group members or the distance between UE A and the group member UE on the map.

Meanwhile, UE A may store the map in advance. In this case, steps S2803 and S2804 in which UE A requests and receives the map information from the map server may be omitted.

Next, case 2 is described.

UE A may transmit/receive the D2D data to/from one or more group member UEs (S2806) and perform the D2D direct communication with any one group member UE (S2807).

One example of the D2D direct communication may correspond to 1:1 communication (the SNS, the phone call, a video call, and the like) or group communication (the SNS, the phone call, the video call, and the like) with a plurality of group member UEs and packets of data of the service are transmitted/received through the D2D communication process.

Herein, although not illustrated in FIG. 28, UE A may be allocated with the resource (that is, the PSSCH resource) for transmitting the D2D data to the base station according to the procedure of FIG. 16 given above and perform the D2D communication with any one group member UE by using the allocated resource in order to transmit the D2D data to the group member UE.

Further, UE A may perform the resource allocation procedure like the example of FIG. 10 given above in order to request the resource allocation for transmitting the D2D data. However, since this case is a case where UE A requests allocating not the PUSCH resource but the PSSCH resource, the PUCCH resource index (that is, the combination of the PRB in which the SR is transmitted, the cyclic shift (CS) applied to the basic sequence (e.g., the ZC sequence) for the frequency domain spread of the SR, and the orthogonal code (OC) for the time domain spread of the SR) distinguished from the SR for requesting the PUSCH resource may be used.

Next, case 3 is described. In case 3, it is assumed that UE A is any one member UE among a plurality of group members.

Case 3 is a case where a coverage warning message is received just before UE A deviates from the representative group UE (e.g., the group leader) when UE A deviates from designated coverage as illustrated in FIG. 27 given above.

As described above, UE A periodically or aperiodically broadcasts the discovery signal (S2808).

The representative group UE may calculate the distance between the representative group UE and the group member UE (including UE A) or the position of the group member UE (including UE A) by using the methods described in FIGS. 17 to 26 given above based on the discovery signal received from the group member UE (including UE A).

When the distance between the representative group UE and the group member UE (including UE A) increases by a predetermined distance or the position of the group member UE (including UE A) deviates from predetermined coverage, the representative group UE transmits the warning message (alternatively, the notification message) by using the D2D communication (S2809).

The representative group UE may be allocated with the resource (that is, the PSSCH resource) for transmitting the D2D data to the base station according to the procedure of FIG. 16 and perform the D2D communication with any one group member UE by using the allocated resource, as described above in order to transmit the D2D data to the group member UE (including UE A). That is, the representative group UE is allocated with the PSSCH resource by receiving the D2D grant and transmits the warning message through the PSSCH resource.

When UE A receives the warning message (alternatively, the notification message) from the representative group UE, UE A displays the received warning message (alternatively, the notification message) on a screen (S2810).

Additionally, when UE A uses the map service in order to go to the position of the representative group UE, verify the position of UE A, or return into predetermined coverage, UE A may transmit the map transmission request message to the map server (S2811) and receive the map information from the map server (S2812).

In addition, UE A may display the position of the representative group UE or the position of UE A on the received map or display a path for guiding to the position of the representative group UE or the predetermined coverage.

In this case, UE A may calculate the distance between UE A and the representative group UE or the position of the representative group UE by using the methods described in FIGS. 17 to 26 given above based on the discovery signal received from the representative group UE. Further, the representative group UE may transmit the position thereof or predetermined coverage information to UE A in step S2809 given above.

Among the procedures of case 1 to case 3 described above, any one procedure may be independently performed or one or more procedures may be simultaneously performed. Further, one or more procedures may be sequentially performed temporally regardless of an order.

Meanwhile, assumed that a criterion for displaying the position of the group member UE moves, in this case, coverage for the group member UE itself continuously moves. For example, a case in which the representative group UE (e.g., the teacher) is not continuously positioned somewhere in the middle but the representative group UE moves together with the group member UE (e.g., the student) is the example. In this case, the same method as above may be implemented based on a fixed D2D beacon device.

FIG. 29 is a diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

Referring to FIG. 29, D2D beacon devices 2910, 2920, and 2930 are fixedly positioned in advance and positions of the respective D2D beacon devices 2910, 2920, and 2930 may be provided to the respective D2D UEs in advance.

Herein, in the specification, the D2D beacon device means a device that periodically or aperiodically transmits the D2D signal while being present at a fixed position.

For example, the D2D beacon device is fixed in places of a famous tourist site to transfer information on each position to the D2D UE or predict even an environment in which each D2D beacon device is installed at a street lamp.

The group member UEs including the representative group UE register the D2D IDs based on a fixed D2D beacon device (e.g., D2D beacon 3 of FIG. 26) which becomes a criterion to generate the group.

In this case, the D2D ID may be registered as two types. Type 1 D2D ID represents the representative group UE (e.g., UE A) 2901 and the other one as Type 2 D2D ID represents group member UEs 2902 other than the representative group UE. Herein, according to a use environment, the number of types may be two or more.

Each UE (that is, type 1 UE and type 2 UE) may display the positions of the group member UEs (including the representative group UE) on the screen based on the D2D beacon device.

In this case, since each UE knows the position of the D2D beacon device in advance, each UE may acquire the position thereof by using a mobile communication network or using a known technology such as the global positioning system (GPS), or the like and display the positions of the group member UEs (including the representative group UE) on the screen based on the D2D beacon device.

Further, the distance from the D2D beacon device may be calculated and the positions of the group member UEs (including the representative group UE) on the screen based on the D2D beacon device by using the methods described in FIGS. 17 to 26 given above with the discovery signal broadcasted from the D2D beacon device.

Boundaries 2903 and 2904 representing a predetermined coverage may be configured based on the position of the fixed D2D beacon device and a plurality of boundaries may be configured according to purposes thereof. FIG. 29 illustrates a case where two boundaries are configured.

Herein, boundary 2 2904 may be configured as the maximum distance (e.g., 1 km) which may be covered by using the D2D technology or configured by the specific distance (e.g., 600 m) determined by the user (e.g., the teacher) of Type 1 UE. Further, boundary 1 2903 may be configured as a boundary of a specific area from which the group members should not deviate due to safety of the group members or specific other reasons. This case means a state (an excessive area to receive a warning message) in which a group member (that is, B 2905) positioned between boundary 1 2903 and boundary 2 2904 are positioned out of coverage desired (that is, configured) by Type 1 UE.

Which flow a related signal has in order to support the service of FIG. 29 will be described with reference to FIGS. 30 and 31 given below.

FIG. 30 is a diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

Referring to FIG. 30, the D2D beacon device periodically or aperiodically broadcasts the discovery signal (S3001).

UE (UE A) having Type 1 D2D ID and UE (UE B) having Type 2 D2D ID calculate the distances from the D2D beacon device based on the discovery signal broadcasted from the D2D beacon device (S3001 and S3003). That is, each UE calculates the distance from the D2D beacon device by using the methods described in FIGS. 17 to 26 given above.

Further, as described above, since each UE knows the position of the D2D beacon device, each UE may obtain the position thereof by using the mobile communication network or using the known technology such as the global positioning system (GPS), or the like and calculate the distance from the D2D beacon device.

Continuously, when it is sensed that UE B deviates from the coverage (boundary 1 2903 of FIG. 29) of the specific area (that is, just before or just after UE B deviates from the coverage) while calculating the distance from the D2D beacon device (S3004), UE B autonomously displays the warning message/notification message to warn the user of UE B (S3005).

Additionally, a fact that UE B deviates from the coverage, that is, information on UE B may be transmitted to UE A through the D2D data channel (S3006). Herein, the information on UE B may include an identity of UE B and indication information for notifying that UE B deviates from the coverage.

Herein, although not illustrated in FIG. 30, UE B may be allocated with the D2D data channel resource (that is, the PSSCH resource) to the base station in order to transmit the information on UE B to UE A through the D2D channel and transmit the D2D data (that is, the information on UE B) to UE A by using the allocated D2D data channel resource. Further, UE B may perform the SNS, the phone call, the video call, and the like with UE A while performing the D2D direct communication.

In addition, although not illustrated in FIG. 30, additionally, when UE B uses the map service in order to go to the position of the representative group UE (that is, UE A), verify the position of UE B, or return into predetermined coverage, UE B may transmit the map transmission request message to the map server and receive the map information from the map server. In addition, UE B may display the position of the representative group UE or the position of UE B on the received map or display a path for guiding to the position of the representative group UE or the predetermined coverage.

FIG. 31 is a diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

Referring to FIG. 31, UE (UE A) having Type 1 D2D ID and UE (UE B) having Type 2 D2D ID broadcast the discovery signal (S3101 and S3102).

The D2D beacon device calculates the distance from each UE based on the discovery signals broadcasted from UE A and UE B (S3103). That is, each D2D beacon device calculates the distance from each UE by using the methods described in FIGS. 17 to 26 given above.

Continuously, when it is sensed that UE B deviates from the coverage (boundary 1 2903 of FIG. 29) of the specific area (that is, just before or just after UE B deviates from the coverage) while calculating the distance from the D2D beacon device (S3104), the D2D beacon device notifies the information on UE B to UE A through the D2D data channel (that is, the PSSCH) (S3105). Herein, the information on UE B may include the identity of UE B and the indication information for notifying that UE B deviates from the coverage.

Further, simultaneously therewith, the D2D beacon device transmits the warning message (alternatively, the notification message) for notifying that UE B deviates from the coverage through the D2D data channel (that is, the PSSCH) (S3106).

Herein, although not illustrated in FIG. 31, the D2D beacon device may be allocated with the D2D data channel resource (that is, the PSSCH resource) to the base station in order to transmit the information on UE B and the warning message to UE A and UE B through the D2D channel and transmit the D2D data (that is, the information on UE B) to UE A by using the allocated D2D data channel resource and simultaneously therewith, the D2D beacon device may transmit the D2D data (that is, the warning message) to UE B.

Meanwhile, a method is described, which represents by which path the group member UE which deviates from the coverage accesses another group member UE or maintains the corresponding UE group on a communication protocol when the group member UE deviates from predetermined coverage while performing a group activity.

Herein, the predetermined coverage may be configured as the maximum distance (e.g., 1 km) which may be covered by using the D2D technology or configured by the specific distance (e.g., 600 m) determined by the user (e.g., the teacher) of the representative group UE. Further, the predetermined coverage may be configured as a boundary of a specific area from which the group members should not deviate due to safety of the group members or specific other reasons.

FIG. 32 is a diagram illustrating a D2D group managing method according to an embodiment of the present invention.

In FIG. 32, it is assumed that one D2D group is generated and the corresponding group member is UE 1 to UE 5. However, it is assumed that UE 1 deviates from the group and D2D connectivity even with UE 2 closest to UE 1 among the group members is impossible.

In this case, as one method for UE 1 to maintain the access to the group members UE 2 to UE 5, when UE 1 is in the RRC idle state, UE 1 attempts accessing the cellular network and establish RRC connection with one UE among the group member UEs.

In FIG. 32, since only UE 3 is in an RRC connected mode, UE 3 may become anchor UE for communication between UE 4 and the group. However, if another member UE which is in the RRC connected state is present other than UE 3 among the group member UEs, the anchor UE may be selected by using an appropriate criterion.

As one example, UE which may make all individual connections of the group members or UE which may make most connections may be selected as the anchor UE by considering a distribution state of the group members. In this case, the 1:1 connection is not actually made but parameters (e.g., reference signal received power (RSRP), a signal to noise ratio (SNR), a signal to interference plus noise ratio (SINR), and the like for the D2D direct link to be in advance is used to be used as the criterion for selecting the anchor UE. For example, each group member UE may periodically (alternatively, voluntarily (by UE trigger)) or aperiodically (alternatively, involuntarily (by base station trigger)) transmit a parameter for the discovery signal received from group member UE other therethan to the base station. The base station may select the anchor UE based on the parameter received from each group member UE.

As another method, UE 1 may select UE that transmits the synchronization signal as the anchor UE for connection with the group. In this case, the eNB may allow the corresponding UE to be in the RRC connected state and make the connection with UE 1. That is, the base station may select UE (that is, the D2D synchronization source or the sidelink synchronization source) that periodically transmits the D2D synchronization signal among the corresponding group member UEs as the anchor UE.

Alternatively, when a cluster head managing the group is present (e.g., UE that serves to transmit the beacon, broadcast primary information, and the like), the cluster head may be designated as group management anchor UE. For example, the base station may select UE that periodically transmits the PSBCH among the group member UEs as the anchor UE.

It should be construed that when UE 1 attempts communication by selecting target UE that intends to perform communication by making the RRC connection among the group member UEs during such a process, UE 1 attempts connection to a group to which the target UE belongs. In addition, it is meant that not destination UE (that is, the target UE) but group anchor UE may be connected during such a process. That is, UE 1 attempts a cellular access to UE 2, but the eNB may make UE 1 be connected to UE 3 by construing such a request. Herein, the connection may be a different procedure and a different state from a 1:1 cellular RRC connection. That is, since UE 1 intends to perform group communication with UE 2, UE 3, UE 4, and UE 5, even though UE 1 requests the communication with UE 2, the eNB configures a communication path with UE 3 and allows UE 3 and UE 2 to perform the communication by the D2D communication. That is, the anchor UE serves even as UE that relays the communication.

When UE 1 which is positioned out of the coverage needs to perform the group communication, all of UE 1 to UE 5 need to be in the RRC connected state in the case of the cellular communication in the related art and thereafter, the group communication is performed. In this case, the D2D group communication becomes actually meaningless. Therefore, when it is considered that the D2D group communication is made to be meaningful and the D2D communication is still performed, a scheme in which only one UE in the group makes the cellular connection is a preferable operation scheme. This will be described in more detail with reference to a drawing given below.

FIG. 33 is a diagram illustrating a D2D terminal group managing method according to an embodiment of the present invention.

In FIG. 33, it is assumed that the target UE (that is, the destination UE) with which UE 2 intends to communicate by making the RRC connection is UE 3 and the base station knows the D2D UE group in advance.

Further, it is assumed that UE 1 is selected as the anchor UE by the aforementioned method. In this case, the anchor UE may be selected by the base station or a rule which the base station and the group member UE share with each other, and the like may be selected.

Referring to FIG. 33, UE 2 transmits to the base station a group communication link setup request including the identity of UE 3 that intends to perform the group communication by making the RRC connection (S3302).

In this case, when UE 2 may be in the RRC_IDLE state, UE 2 is transitioned to the RRC_CONNECTED state according to the procedures of FIGS. 8 and 9 given above (S3301) and UE 2 may transmit the group communication link setup request message to the base station (S3302).

Since UE 1 is the anchor UE as described above, the base station transmits a group communication link setup message to UE 1 (S3303).

UE 1 transmits to the base station a link communication link setup response message as a response to the D2D link setup message (S3305).

In this case, when UE 1 may be in the RRC_IDLE state, UE 1 is transitioned to the RRC_CONNECTED state according to the procedures of FIGS. 8 and 9 given above (S3304) and UE 1 may transmit the group communication link setup response message to the base station (S3305).

UE 2 establishes (that is, cellular-connects) the group communication link with UE 1 through the base station.

Thereafter, UE 2 performs the group communication with one or more group member UEs through UE 1. In other words, when UE 2 transmits data to group 1 through the group communication link (that is, the cellular connection) in order to transmit the data to one or more group member UEs, UE 1 transmits the data of UE 2 to one or more group member UEs through the D2D direct communication, that is, the PSSCH. Further, the reverse thereto is possible.

FIG. 34 is a diagram illustrating a D2D group managing method according to an embodiment of the present invention.

FIG. 34 illustrates a case where corresponding UE deviates from coverage of UE that is present at the center of group A, but does not deviate from a group periphery, in particular, the coverage of UE 2 close to UE 1.

In this case, proposed is a method in which group A is normally operated and UE 2 continuously relays a packet of group A to support UE 1 to operate as a member of group A. That is, the D2D direct communication link is established between UE 1 and UE 2, UE 2 and the D2D direct communication link is established between the group members UE 3, UE 4, and UE 5), and UE 2 relays data between UE 1 and one or more group members UE 3, UE 4, and UE 5.

In this case, an additional cellular connection illustrated in FIGS. 32 and 33 need not be maintained. In the case where cellular coverage is not valid, an effect of extending the coverage of group A may be obtained. In such a group management, a technical reward or a monetary reward may be provided to the corresponding relay UE.

Meanwhile, the present invention proposes a method for transmitting to a specific server system “information such as D2D IDs, and like collected from a UE, a black box, a vehicle, and the like supporting a D2D function, which are positioned nearby” based on the person to an accident “for past predetermined time around an accident occurrence time” when particular situations including such as an emergency situation, and the like occur. As such, the present invention relates to a public interest pursuit service which assists solving the emergency situations by providing an opportunity to request and secure detailed information on the then accident situation, which is recorded in the D2D UE, the black box, and the vehicle positioned to be proximate to the emergency situation by finding an actual device ID or a user through deciphering a D2D ID which is proximate to an emergency situation occurrence point and a technical method for implementing the same.

More accurate and reliable information than a statement of a witness which witnesses a site of the emergency situation may be secured through a process of generating and collecting the D2D signal and finding the corresponding person (UE) and a ground to definitely establish the rights and wrongs which may occur due to lack of evidence may be secured.

As another implementation example of a proposal method, the proposal method may be implemented even by a process in which the person to the accident, the UE, and the vehicle directly transmit a request signal to receive an accident related record in an adjacent witness, the UE, the vehicle, the black box. Rapid signal transmission is required so as to prevent persons or vehicles positioned at an accident site from deviating from D2D coverage. In this case, a method that automatically transmits the signal by recognizing a vehicle situation by interlocking with a collision prevention system of the vehicle, and the like may be together used.

Herein, in describing the present invention, even though detailed description of the method for transmitting the D2D discovery signal (that is, the PSDCH) or the D2D direct communication data is not mentioned, the aforementioned transmission method (in particular, the method according to FIGS. 11 to 16) may be similarly applied.

Hereinafter, in describing the present invention, an adjacent UE positioned within predetermined coverage (e.g., a maximum effective distance capable of securing the D2D ID) of a location where the emergency situation occurs may be appreciated as the D2D UE group.

FIG. 35 is a diagram illustrating a user interface at the time of implementing a method for collecting a D2D ID proximity-based notification according to an embodiment of the present invention.

FIG. 35(a) illustrates the user interface (UI) displayed on the screen of UE (UE A) of the person directly concerned, which is placed in the emergency situation just after the emergency situation occurs. The UI of FIG. 35(a) may be displayed on the screen of the UE when an associated application is driven.

In FIG. 35(a), A 3501 represents a position (that is, the position of UE A) of the UE of the person directly concerned or a position where the emergency situation occurs and a dotted line (coverage 3503) is a maximum effective distance (e.g., 1 km) capable of securing the D2D ID of the UE which broadcasts the discovery signal nearby. Further, the position of an adjacent UE 3502 transmitting the discovery signal is displayed within the coverage 3503 capable of securing the D2D ID.

A technique capable of verifying its own position includes a method for using a GPS. In addition, a LTE/LTE-A positioning technique may be used. That is, a technique of verifying positions of UEs by receiving a positioning reference signal (PRS) transmitted by a neighboring base station to analyze a difference in arrival time of the received signal may be used.

However, the technique has a limit in that the person directly concerned just verifies the position thereof and may not verify the positions of other persons. As one method for overcoming the limit, a D2D technique may be used. For example, the D2D UE transmits the discovery signal to adjacent base stations based on a transmission time acquired by performing individual synchronization and the D2D UE may find an absolute position thereof by analyzing a difference in arrival time of signals transmitted according to different base station timings and similarly, determine even the absolute positions of other UEs. In this case, it is assumed that the D2D UE has known positional information of the base station in advance (see FIGS. 17 to 26 given above).

The position of UE A or an adjacent UE (including UE B) obtained by such a method is displayed on the screen of UE A.

UE A obtains the D2D IDs of the adjacent UEs that transmit the discovery signal and transmits the obtained D2D IDs to the server (e.g., the server of a police (a public institution or a server management company to which the public institution entrusts a role), and the like). Herein, the server may be implemented as the base station or a network node (e.g., MME or an M2M server).

As described above, the D2D ID is transferred while being included in the discovery message. In this case, UE A may transmit to the server information associated with the emergency situation, such as an emergency situation type, an emergency situation occurrence time, an emergency situation occurrence position, or an emergency situation strength/intensity together with the obtained D2D ID.

As such, in respect to the information collected by UE A, a case where the information collected by UE A is automatically transmitted when the emergency situation occurs and a case where the collected information is manually directly transmitted may be considered.

The reason for using the automatic transmission is that occurs because as the person suffers from a sudden emergency situation, the person may not directly request an SOS, that is, a case where the person may not operate the terminal, in this case, an SOS signal needs to be automatically transmitted (that is, the D2D ID needs to be transmitted to the server) by sensing body states (a heartbeat, a blood flow, and the like) of the person directly concerned with the emergency situation or impact, noise, and a surrounding situation at the time when the emergency situation. For example, when a difference from normal times is sensed by sensors (e.g., sensors capable of sensing the heartbeat, a pulse, a breath, a blood pressure, and the like, sensors capable of sensing an acceleration, the impact, and the like, sensors capable of sensing a surrounding temperature, noise, and the like) mounted on UE A by a threshold or more is sensed, it may be determined that the emergency situation occurs and the obtained D2D ID of the adjacent UE may be transmitted to the server. On the contrary, in the case where the person directly concerned manually transmits the SOS, when the user directly presses a transmission button, the obtained D2D IDs of the UEs around the emergency situation occurrence position are transmitted to the server.

Personal information of the user of the corresponding UE is found from the transmitted D2D IDs for the server to determine whether accident associated information may be provided by establishing a contact with the respective users. That is, a user (that is, UE) that belongs to a registration list 3505 of service joining users is found among the D2D IDs included in a D2D ID 3504 requested by UE A to determine whether the accident associated information may be provided.

FIG. 35(c) illustrates the U displayed on the screen of UE (UE B) (e.g., an emergency situation witness (a vehicle passenger, a witness of a surrounding street, and the like)) which is proximate to the location where the emergency situation occurs just after the emergency situation occurs. In FIG. 35(c), B 3506 represents the position of the user's own terminal and a position 3507 where the emergency situation occurs is together displayed.

That is, when the server transmits a query message for querying whether the emergency situation associated information may be provided to UE B included in the registration list 3505, a query message window of FIG. 35(c) may be displayed on the screen in UE B. Further, the server may transmit even the information including the emergency situation occurrence time, the emergency situation occurrence position, and the like to UE B together with the query message.

In spite of the D2D UE that is preset within the coverage of the UE which suffers from the emergency situation, responding to a request will follow a free will of a person which receives the request. By considering such a point, an access method may be considered, in which the user/UE which intends to use the corresponding service in advance agrees to has his/her intention to provide his/her accident witness/recording information when the accident occurs. In this case, proposed is that the D2D ID is collected by distinguishing UE that agrees to provide the information among the D2D UEs that are present in the coverage of the accident.

In order to implement the proposal, the D2D discovery signal which an information providing consenter UE transmits needs to include indication information notifying information providing agreement. A specific field on a discovery signal format is defined to be used for such a purpose.

As another implementation method, a method is also available, in which the server compares the D2D ID collected from UE A and the D2D ID of the information providing consent to not record but delete a D2D ID which is not consented. That is, the above registration list 3505 may mean the user/UE that agrees to providing the information.

When the information collected by the server is a lot, usage of a memory increases, and as a result, implementation cost increases. Therefore, it is preferable that the adjacent collected D2D ID and associated information are minimized and stored and temporarily kept. In such an aspect, it is preferable to secure only a useful D2D ID and seek an assistance requester by querying the information to the server.

Further, the indication information may indicate that even the user which agrees to provide the information may not provide the information due to a personal circumstances or temporarily and it should be determine whether the information is recorded and kept by collecting all of the conditions. In this case, a used indication bit may be similar to the aforementioned information providing agreement bit, but the indication bit may be implemented by defining a separate bit field. Further, the above information providing agreement indication bit and the information providing possible indication bit may not be just the bit field but may be transmitted in combination with specific information and transmitted through making with a specific bit.

In addition, in spite of the users which agree to providing the information in advance, UE A may transmit only D2D IDs of some user among the corresponding users to the server. In this case, for the purpose of facilitating system implementation, a method for selecting K D2D IDs is required when a transmission packet is configured so as to transmit only a maximum of K D2D IDs.

For example, a strength (e.g., RSRP, and the like) of a received signal, a signal to noise ratio (SNR), a signal to interference plus noise ratio (SINR), and the like become a reference, and as a result, only a D2D ID of UE in which a parameter is equal to or more than a threshold may be transmitted to the server.

One reason for determining the size of the packet is that in the case of emergent message transmission, it is preferable to transmit the packet having a size suitable for a limited resource previously allocated in order to rapidly transmit the message to a previously allocated resource area. In such an access method, a packet size suitable for the size of a reserved resource may be predetermined in advance. Consequently, the number of D2D IDs to which the packet may be transmitted cannot but be limitative.

In some accidents, in particular, in the case of an accident associated with public safety, the accident associated information providing may be forcibly executed so as to oblige the accident associated information providing. When such a service is activated, cost and time required for finding the witness is anticipated to be saved and the activation of the service will assist even keeping public order.

In this case, the person to the accident and the witness need not take the contact with each other. The collection of the D2D ID may be implemented even by a process in which the D2D ID is provided to the police and the police performs the subsequent accident treatment. In this case, since there is a possibility that fairness and reliability will be damage while the person directly concerned meets and provides the information, it may be more preferable that the public institution undertakes the task.

A signal flow associated with FIG. 35 may be divided into two cases and hereinafter, the two cases will be described with reference to FIGS. 36 and 37.

FIG. 36 is a diagram illustrating a D2D collecting method according to an embodiment of the present invention.

FIG. 36 illustrates an example of a case where a reporter uses the service, the reporter needs to manually make a report by personally executing the application which corresponds to a case where automatic sensing of the emergency situation or associated information may not be input. Further, such a case may be regarded as a case where when automatic transmission is turned off, manual transmission may be manually performed.

As mentioned above, it is assumed that UE (having an LTE D2D function such as the UE of the reporter receives an ID which meets a condition among LTE D2D discovery signals of adjacent (e.g., within a radius of 1 km) UEs and stores the received ID therein together with time information in real time at normal times (through option selection or by default on). A storage time or a memory allocation capacity is determined by a manufacturer or determined by a request or a regulation of an external agency such as a communication provider, or the like. Alternatively, an information retention time/period may be determined according to the type of the information.

Referring to FIG. 36, UE A (e.g., a reporter UE or an emergency situation concerned person terminal) receives the D2D discovery signal periodically or aperiodically transmitted from proximate UE B (e.g., a witness vehicle or UE) (S3601).

UE A senses (or detects) that an event occurs (S3602). Herein, the event represents a case where the emergency situation concerned person or an LTE D2D device user around the emergency situation executes an emergency reporting function embedded in the emergency situation concerned person UE when the emergency situation such as a traffic accident, or the like occurs. For example, execution of an application of performing a function to collect the D2D ID of the proximate UE/vehicle or input of a special button having an emergency call function, or the like may correspond to the occurrence of the event. Herein, when a counterpart UE (a predetermined UE) executes the emergency reporting function of UE A, the method is preferably implemented such a manner that the counterpart UE executes the corresponding emergency reporting function even though the counterpart UE does not know a password of UE A.

When the event occurrence is sensed like step S3502, D2D UE group information within a distance (e.g., within the radius of 1 km) corresponding to D2D coverage based on the position of UE A (alternatively, UE A user) is transmitted to the server (e.g., a police server) (S3503).

That is, a D2D UE group may be constituted by one or more adjacent UEs receiving the discovery signal of UE A.

Herein, the D2D UE group information may include the D2D ID of the UE or vehicle around the location (alternatively, the position of the concerned person UE) where the emergency situation occurs, the position (e.g., the position of the reporter) of UE A, the position of the emergency situation site, or emergency situation associated information. In this case, the D2D IDs mean D2D IDs of discovery signals received and stored before or after the emergency reporting function is executed. Further, the emergency situation associated information may include an emergency situation type, an emergency situation occurrence time, an emergency situation occurrence position, or an emergency situation strength/intensity.

Additionally, when there is no adjacent person, that is, when the D2D ID of the adjacent UE/vehicle may not be collected, UE A may notify to the server that there is no searched D2D ID. In addition, only the position of UE A (alternatively, the UE A user) and emergency situation associated information may be transmitted to the server. When other adjacent D2D UE/vehicle (that is, UE B) may determine a situation of obtaining the D2D ID of the accident concerned UE (that is, UE A) by using the information, the other adjacent D2D UE/vehicle may obtain adjacent UE information (that is, the D2D ID) collected by the adjacent D2D UE/vehicle (that is, UE B). In addition, the situation of the accident may be determined based on the obtained information and the accident may be solved.

The server receives the D2D UE group information from UE A to receive that the emergency situation occurs (S3504).

When the D2D UE group information including the D2D ID of the adjacent UE/vehicle is received while the server receives an emergency situation occurrence history, the server searches adjacent UE/vehicle (e.g., the witness) matching the D2D ID (S3505).

The server registers the searched adjacent UE/vehicle in an adjacent witness list, the server is connected with the user of the corresponding UE/vehicle through a call or message (S3506), and the server transmits the emergency situation associated information (S3507). As described above, the emergency situation associated information may include the emergency situation type, the emergency situation occurrence time, the emergency situation occurrence position, or the emergency situation strength/intensity.

For example, the information on the UE/vehicle around the emergency situation is collected as described above, and as a result, the police may indicate a policeman most adjacent to a region from which a report is received to patrol the corresponding region and in this case, the police may transmit the position of the reporter. The adjacent witness may accept or reject a traffic accident assistance request announced from the police. When the adjacent witness accepts or rejects the assistance request, whether the witness accepts or rejects the assistance request is automatically transmitted to the police server. When the witness accepts the assistance, the police treats the accident by receiving a statement of the witness by a general method (phone calling or the message). When the witness rejects the assistance, the witness is deleted from an adjacent witness list. However, when it is determined that the witness is important, the witness may be kept in the adjacent witness list apart from the response contents.

FIG. 37 is a diagram illustrating a D2D ID collecting method according to an embodiment of the present invention.

FIG. 37 illustrates an example in which when the occurrence of the emergency situation is sensed, the service is automatically executed. For example, in the case of a vehicle accident, a chip that performs the D2D communication function may be built in the vehicle or whether the accident occurs in the vehicle may be sensed through an accessory.

Referring to FIG. 37, UE A (e.g., a reporter UE or emergency situation concerted person UE) receives the D2D discovery signal periodically or aperiodically transmitted from proximate UE B (e.g., a witness vehicle (device) or UE) (S3701).

UE A senses (or detects) that an event occurs (S3702). Herein, the event means sensing the emergency situation by a sensor mounted on the D2D UE of the emergency situation occurrence concerned person when the emergency situation occurs.

As such, when the D2D UE detects the event, the emergency reporting function embedded in the device is automatically executed.

As one case of D2D resource allocation, a plurality of resource areas is allocated in a resource pool form from the base station in advance and when the D2D UE actually transmits data, the data is transmitted through a resource arbitrarily selected in a resource pool (resource allocation mode 2). However, when the number of UEs increases in the case where the UE personally arbitrarily selects a transmission resource, multiple UEs may simultaneously select and transmit the same resource, and as a result, a collision may occur in data transmission. Therefore, the resource allocation mode may cause a situation in which an emergency signal may not be transmitted when the emergency situation occurs.

As one method for improving the problem, resource allocation for D2D data is individually performed for each UE in real time. That is, when the D2D UE intends to transmit the D2D data, the D2D UE may request the resource allocation for transmitting the D2D data, acquire an approval for the request, and use an approved specific resource (resource allocation mode 1). However, due to a procedure in which a resource for transmitting the D2D data is allocated from the base station, the delay may occur and signaling overhead may increase. In particular, in order to the emergency signal, the emergency signal needs to be able to be transmitted anytime, but the delay may become a problem in transmitting the emergency signal.

Accordingly, a predetermined resource area is allocated as a resource area for transmitting the emergency signal and the limited resource area (an emergency resource area or a common resource) is used only in the case of the emergency situation. The emergency resource area may be set as a partial area in the resource pool for the D2D data (that is, the PSSCH) and set regardless of the resource pool for the D2D data (that is, the PSSCH).

Two following methods for using the emergency resource area may be considered.

First, the UE may arbitrarily select a specific resource of the emergency resource area without a resource allocation request (that is, SR) of the UE and transmit the D2D data (that is, the emergency signal) in the selected resource. Further, the UE may first perform an emergency resource request to the base station (alternatively, the network node) and receive an authentication of the base station (alternatively, the network node) and thereafter, transmit the emergency signal in the allocated resource.

In the case of the former, a situation may occur, in which multiple UEs indiscreetly transmit the emergency signal by a simple method or without a resource allocation request procedure at an accident occurrence location. In this case, a situation in which all emergency signals are blocked may be caused.

Accordingly, in spite of the emergency signal, it is preferable that a resource use request is rapidly transmitted to the base station (alternatively, the network node) and the emergency signal is transmitted through the resource allocated through an authentication like the latter method in using an emergency resource.

When the event occurrence is detected in step S3702 given above, UE A automatically requests verifying whether the emergency resource area (alternatively, the common resource) may be used to the base station (alternatively, the network node) (S3903).

In this case, information (indication) notifying that the transmitted signal is the emergency signal may be included in the emergency resource request. For example, in a PUCCH resource in which the emergency resource request may be transmitted so as to be distinguished from the SR in the related art, at least one of a PRB in which the SR is transmitted in the related art, a cyclic shift (CS) applied to the basic sequence (e.g., ZC sequence) for frequency domain spread of the SR in the related art, and an orthogonal code (OC) for time domain spread of the SR in the related art may be differently configured. The information may be regarded as a right to use an emergency signal dedicated resource area or control information included to acquire an authority to request resource allocation for using the emergency signal resource area.

The emergency resource area may be allocated by a prior resource allocation method (e.g., by system information (SIB or MIB) or high layer signaling). In this case, when there are a lot of pre-allocated resources and there is almost little emergency signal transmission, the corresponding resource may be wasted. Contrary to this, when the pre-allocated resource is short, a probability that the emergency signal will not be transmitted may increase. Accordingly, the size of the allocated resource area needs to be able to be controlled.

When the base station receives a use request of the emergency resource area (alternatively, the common resource) from UE A, the base station (alternatively, the network node) performs authentication of UE A (alternatively, the UE A user) that transmits the request with respect to the received emergency resource area use request and approves the use of the emergency resource area to UE A when the authentication is successful (S3704). In this case, in order to perform UE (alternatively, the user) authentication, the information (indication) notifying that the transmitted signal is the emergency signal may be used.

UE A that receives the approval of the emergency resource area use from the base station (alternatively, the network node) transmits the emergency signal to adjacent UE (that is, UE B) which belongs to the D2D UE group (S3705). That is, UE A transmits the emergency signal to UE B (that is, the adjacent UE) on the D2D discovery message (that is, the PSDCH) or the D2D data channel (that is, the PSSCH).

Here, the D2D UE group may be constituted by one or more adjacent UEs receiving the discovery signal of UE A.

Herein, as the emergency signal, the information (indication) notifying that the transmitted signal is the emergency signal may be used. For example, the indication may be transferred in a specific bit field of the D2D discovery message (that is, the PSDCH) or the D2D data channel (that is, the PSSCH) or the indication may be masked with a predetermined sequence.

UE (including UE B) around UE A may receive the emergency signal from UE A. Further, the UE (including UE B) around UE A may receive a notification of the emergency situation associated information from the base station (alternatively, the network node) through the emergency reporting function.

UE B that receives the emergency signal may accept or reject the assistance request for the received emergency signal and when UE B accepts or rejects the assistance request, UE B transmits a message indicating whether the assistance is accept to UE A (S3706).

When UE B accepts the assistance, UE A performs D2D direct communication through the secured emergency resource area when communication with UE B is available by a D2D method, but UE A performs communication with UE B by a general method (the phone call and the message) when the communication is unavailable by the D2D method (S3707).

For example, the information on the UE/vehicle around the accident is collected as described above, and as a result, the police may indicate a policeman most adjacent to a region from which a report is received to patrol the corresponding region and in this case, the position of the reporter may be transmitted to the policeman which performs patrolling. However, when the user of UE that receives the D2D emergency signal is the policeman, the policeman may immediately go to a site without a separate indication.

General Wireless Communication Apparatus to which Present Invention can be Applied

FIG. 38 is a block diagram of a wireless communication apparatus according to an embodiment of the present invention.

Referring to FIG. 38, the wireless communication system includes a base station/network node 3810 and multiple terminals 3820 (alternatively, a D2D device). Herein, one example of the network node may correspond to an MME or M2M server.

The base station/network node 3810 includes a processor 3811, a memory 3812, and a communication unit 3813.

The processor 3811 implements a function, a process, and/or a method which are proposed in FIGS. 1 to 37 given above. Layers of a wired/wireless interface protocol may be implemented by the processor 3811. The memory 3812 is connected with the processor 3811 to store various pieces of information for driving the processor 3811. The communication unit 3813 is connected with the processor 3811 to transmit and/or receive a wired/wireless signal. In particular, when the base station/network node 3810 is a base station, the communication unit 3813 may include a radio frequency (RF) unit for transmitting/receiving the wireless signal.

The terminal 3820 includes a processor 3821, a memory 3822, and a communication unit (alternatively, a radio frequency (RF) unit) 3823. The processor 3821 implements a function, a process, and/or a method which are proposed in FIGS. 1 to 37 given above. The layers of the radio interface protocol may be implemented by the processor 3821. The memory 3822 is connected with the processor 3821 to store various pieces of information for driving the processor 3821. The communication unit 3823 is connected with the processor 3821 to transmit and/or receive a radio signal.

The memories 3812 and 3822 may be positioned inside or outside the processors 3811 and 3821 and connected with the processors 3811 and 3821 through various well-known means. Further, when the base station/network node 3810 is the base station, the terminal 3820 may have a single antenna or multiple antennas.

FIG. 39 is a block diagram of another terminal according to an embodiment of the present invention.

Referring to FIG. 39, a terminal 3900 may include a wireless communication unit 3910, an input unit 3920, a sensing unit 3940, an output unit 3950, a memory 3960, an interface unit 3970, a control unit 3980, and a power supply unit 3990. The components illustrated in FIG. 39 are not essential components. Therefore, a mobile terminal having more components therethan or less components therethan may be implemented.

Hereinafter, the components will be described in sequence.

The wireless communication unit 3910 may include one or more modules that enable wireless communication between the terminal 3900 and the wireless communication system or between the terminal 3900 and a network on which the terminal 3900 is positioned. For example, the wireless communication unit 3910 may include a broadcast receiving module 3911, a mobile communication module 3912, a wireless Internet module 3913, a short-range communication module 3914, and a positional information module 3915.

The broadcast receiving module 3911 receives a broadcast signal and/or broadcast associated information from an external broadcast management server through a broadcasting channel.

The broadcasting channel may include a satellite channel and a terrestrial channel. The broadcast management server may mean a server that generates and transmits the broadcast signal and/or broadcast associated information or a server that receives a pre-generated broadcasting signal and/or broadcast associated information and transmits the received broadcasting signal and/or broadcast associated information to the terminal. The broadcasting signal includes a TV broadcasting signal, a radio broadcasting signal, and a data broadcasting signal and may include even a broadcasting signal of a form in which the broadcasting signal is combined with the TV broadcasting signal or the radio broadcasting signal.

The broadcast associated information may mean information associated with the broadcasting channel, a broadcasting program, or a broadcasting service provider. The broadcast associated information may be provided eve through a mobile communication network. In this case, the broadcast associated information may be received by the mobile communication module 3912.

The broadcast associated information may be present in various forms. For example, the broadcast associated information may be present in a form such as an electronic program guide (EPG) of digital multimedia broadcasting (DMB) or an electronic service guide of digital video broadcast-handheld (DVB-H).

The broadcast receiving module 3911 may receive a digital broadcasting signal by using digital broadcasting systems including, for example, digital multimedia broadcasting-terrestrial (DMB-T), digital multimedia broadcasting-satellite (DMB-S), media forward link only (MediaFLO), digital video broadcast-handheld (DVB-H), integrated services digital broadcast-terrestrial (ISDB-T), and the like. Of course, the broadcast receiving module 3911 may be configured to be suitable for other broadcasting systems in addition to the aforementioned digital broadcasting systems.

The broadcasting signal and/or broadcast associated information received through the broadcast receiving module may be stored in the memory 3911.

The mobile communication module 3912 transmits/receives the wireless signal to/from at least one of the base station, an external terminal, and the server on the mobile communication network. The wireless signal may include a voice call signal, a video call signal, or various types of data depending on transmission/reception of a text/multimedia message.

The wireless Internet module 3913 which represents a module for a wireless Internet access may be internally or externally installed in the terminal 3900. As the wireless Internet technology, wireless LAN (WLAN) (Wi-Fi), wireless broadband (Wibro), world interoperability for microwave access (Wimax), high speed downlink packet access (HSDPA), or the like, may be used.

The short-range communication module 3914 represents a module for short-range communication. As short range communication technology, Bluetooth, radio frequency identification (RFID), infrared data association (IrDA), ultra wideband (UWB), ZigBee, or the like may be used.

The positional information module 3915 is a module for obtaining the position of a mobile terminal and a representative example of the positional information module 5615 includes a global positioning system (GPS).

The input unit 3920 is used for an audio signal or video signal input or a user input. The input unit 3921 may include a camera 3922 and a microphone 5622 for the audio signal or video signal input.

The camera 3921 processes an image frame such as a still image or a motion picture acquired by an image sensor in a video call mode or a pick-up mode. The processed image frame may be displayed in a display unit 3951.

The image frame processed by the camera 3921 may be stored in the memory 3960 or transmitted to the outside through the wireless communication unit 3910. Two or more cameras 3921 may be provided according to a use environment.

The microphone 3922 receives an external sound signal and processes the received external sound signal as electrical voice data by a microphone in a call mode, a recording mode, a voice recognition mode, or the like. The processed voice data is converted into a form transmittable and output to a mobile communication base station through the mobile communication module 5612 in the case of the call mode. Various noise removing algorithms for removing noise generated in the course of receiving the external sound signal may be implemented in the microphone 3922.

The user input unit 3923 generates input data for controlling an operation of the terminal by a user. The user input unit 130 may include a keypad, a dome switch, a touch pad (resistive/capacitive), a jog wheel, a jog switch, and the like.

The sensing unit 3940 generates a sensing signal for controlling the operation of the terminal 3900 by current states of the terminal 3900, which include an opening/closing state of the terminal 3900, the position of the terminal 3900, where the user contacts, an orientation of the terminal, acceleration/deceleration of the terminal, and the like. For example, when the terminal 3900 is a slide phone type, the sensing unit 3940 may sense whether a slide phone is opened or closed. Further, the sensing unit 3990 may sense whether the power supply unit 3970 supplies power, whether the interface unit 3970 is connected with an external apparatus, and the like. Meanwhile, the sensing unit 3940 may include a proximate sensor, a sensor that may sense a heart rate, a pulse, a breath, a blood pressure, and the like of the user of the terminal 3900, and a sensor that may sense a temperature, noise, and the like around the terminal 3900.

The output unit 3950 which is used for generating an output related with sight, hearing, or touch may include the display unit 3951, a sound output unit 3952, an alarm unit 3953, and a haptic module 3954.

The display unit 3951 displays (outputs) information processed in the terminal 3900. For example, when the mobile terminal is in the call mode, the display unit 3951 displays a user interface (UI) or a graphic user interface (GUI). When the terminal 3900 is in the video call mode or the pick-up mode, the display unit 5651 displays a picked-up or received image, the UI, and the GUI.

The display unit 3951 may include at least one of a liquid crystal display (LCD), a thin film transistor-liquid crystal display (TFT LCD), an organic light-emitting diode (OLED), a flexible display, and a 3D display.

Some of the displays may be configured as a transparent or light transmissive type to view the outside through the displays. This may be called a transparent display and a representative example of the transparent display includes a transparent OLED (TOLED), and the like. The display unit 3951 may be configured in a rear structure and a light transmissive structure. By such a structure, the user may view an object positioned in the rear of a terminal body through an area occupied by the display unit 3951 of the terminal body.

According to the implementation form of the terminal 3900, two or more display units 3951 may be present. For example, in the terminal 3900, a plurality of displays may be separated from each other or integrally disposed on one surface, and further, disposed on different surfaces, respectively.

When the display unit 3951 and a sensor (hereinafter, referred to as a ‘touch sensor’) sensing a touch operation form a mutual layer structure (hereinafter, referred to as a ‘touch screen’), the display unit 3951 may be used as an input device in addition to the output device. The touch sensor may have forms including, for example, a touch film, a touch sheet, a touch pad, and the like.

The touch sensor may be configured to convert pressure applied to a specific portion of the display unit 3951 or a change in capacitance generated at the specific portion of the display unit 3951 into an electrical input signal. The touch sensor may be configured to detect touch pressure as well as touched position and area.

When there is a touch input for the touch sensor, a signal(s) corresponding to the touch input is(are) sent to a touch controller. The touch controller processes the signal(s) and thereafter, transmits data corresponding thereto to the control unit 3980. As a result, the control unit 3980 may know which area of the display unit 3951 is touched.

The proximate sensor may be displayed in an internal area of the mobile terminal, which is covered by the touch screen or in the vicinity of the touch screen. The proximate sensor represents a sensor that detects whether an object approaching a predetermined detection surface or an object which exits in the vicinity of the detection surface is present without a mechanical contact by using force of an electronic system or infrared rays. The proximate sensor is longer in life-span and higher in utilization than a contact type sensor.

Examples of the proximate sensor include a transmissive photoelectric sensor, a direct reflective photoelectric sensor, a mirror reflective photoelectric sensor, a high-frequency oscillation type proximate sensor, a capacitive proximate sensor, a magnetic proximate sensor, an infrared proximate sensor, and the like. When the touch screen is capacitive, the touch screen is configured to detect proximity of a pointer due to a change in electric field depending on the proximate of the pointer. In this case, the touch screen (touch sensor) may be classified as the proximate sensor.

In the aforementioned embodiments, the elements and characteristics of the present invention have been combined in specific forms. Each of the elements or characteristics may be considered to be optional unless otherwise described explicitly. Each of the elements or characteristics may be implemented in such a way as not to be combined with other elements or characteristics. Furthermore, some of the elements and/or the characteristics may be combined to form an embodiment of the present invention. Order of operations described in connection with the embodiments of the present invention may be changed. Some of the elements or characteristics of an embodiment may be included in another embodiment or may be replaced with corresponding elements or characteristics of another embodiment. It is evident that in the claims, one or more embodiments may be constructed by combining claims not having an explicit citation relation or may be included as one or more new claims by amendments after filing an application.

An embodiment of the present invention may be implemented by various means, for example, hardware, firmware, software or a combination of them. In the case of implementations by hardware, an embodiment of the present invention may be implemented using one or more Application-Specific Integrated Circuits (ASICs), Digital Signal Processors (DSPs), Digital Signal Processing Devices (DSPDs), Programmable Logic Devices (PLDs), Field Programmable Gate Arrays (FPGAs), processors, controllers, microcontrollers and or microprocessors or all of them.

In the case of implementations by firmware or software, an embodiment of the present invention may be implemented in the form of a module, procedure, or function for performing the aforementioned functions or operations. Software code may be stored in the memory and driven by the processor. The memory may be placed inside or outside the processor, and may exchange data with the processor through a variety of known means.

It is evident to those skilled in the art that the present invention may be materialized in other specific forms without departing from the essential characteristics of the present invention. Accordingly, the detailed description should not be construed as being limitative from all aspects, but should be construed as being illustrative. The scope of the present invention should be determined by reasonable analysis of the attached claims, and all changes within the equivalent range of the present invention are included in the scope of the present invention.

INDUSTRIAL APPLICABILITY

In the wireless communication system, the example of the D2D UE group management method applied to the 3GPP LTE/LTE-A system is primarily described, but the D2D UE group management method can be applied to various wireless communication systems in addition to the 3GPP LTE/LTE-A system. 

The invention claimed is:
 1. A method for managing a device to device (D2D) terminal group in a wireless communication system, the method performed by a first terminal which belongs to the D2D terminal group and comprising: receiving, from a second terminal which belongs to the D2D terminal group, a discovery signal on a physical sidelink discovery channel (PSDCH); calculating a position of the second terminal by using the discovery signal; and displaying the position of the second terminal based on a position of the first terminal, wherein, when it is detected that a third terminal which belongs to the D2D terminal group deviates from a D2D coverage of the D2D terminal group, an anchor terminal for relaying data between the third terminal and a terminal which belongs to the D2D terminal group among the terminals which belong to the D2D terminal group is configured.
 2. The method for managing a D2D terminal group of claim 1, further comprising: transmitting a warning message to the second terminal on a physical sidelink shared channel (PSSCH) when the second terminal is spaced apart from the first terminal by a predetermined distance.
 3. The method for managing a D2D terminal group of claim 1, wherein the third terminal and the anchor terminal are connected through a cellular link and the anchor terminal and the terminal which belongs to the D2D terminal group are connected through a D2D link.
 4. The method for managing a D2D terminal group of claim 1, wherein the anchor terminal is selected as a terminal having reference signal received power (RSRP), a signal to noise ratio (SNR), or a signal to interference plus noise ratio (SINR) for the D2D link between the terminals which belong to the D2D terminal group, which is the highest.
 5. The method for managing a D2D terminal group of claim 1, wherein the anchor terminal is selected as a terminal that transmits a D2D synchronization signal.
 6. The method for managing a D2D terminal group of claim 1, wherein the anchor terminal is selected as a terminal that transmits a physical sidelink broadcast channel (PSBCH). 